This page has been accessed
times since 24 September 2001.
It's sad but true ... the installation defaults for OS/2
are set up to emphasize a glossy appearance rather than performance.
By changing various parts of the system configuration, you can get
a much speedier system.
Also available in Japanese thanks to Toda Haruo.
- 1999-08-16: Moved this page to a better server.
- 1998-09-25: Fixed a couple of broken links.
(Yes, I'm aware that a few other things on this page need
updating. I hope to clean up this page soon, but for now I don't
have the time.)
- 1997-08-14: PIIXIDE disk driver. Warning about Windows TEMP
directories. Fix for the image association bug.
- 1997-08-14: The "new" graphic is back, but this time it's coded by
month, like this:
- 97/05/22: Minor change to CACHE.EXE parameters.
- 97/05/13: Added link to IBM's tuning pages. New suggestion
about disabling lazy writes to circumvent a possible HPFS bug.
REXX script to deregister IBM Works classes.
- 97/05/13: I've given up on the "new" graphic, it was too hard to
keep track of how long it should stay displayed on a new item.
The information on this page is aimed at users of OS/2 Warp 4;
but it comes from experience with all versions of OS/2
since version 2.0, so a lot of it is not version-specific.
Most of the tips are not original with me, they came from various net.helpers.
Unfortunately I didn't think to keep track of their names, so
I'll have to confine my acknowledgments to a big thanks to the
entire OS/2 community out there.
The programs mentioned here are available from the usual OS/2
archive sites. See my list of
recommended freeware for more details.
Some useful tools
Changes that everyone needs
- Before making any dangerous changes to your system, back
up the crucial system files as follows:
You shouldn't leave archiving turned on, for two reasons:
it slows down the boot process, and it creates the risk
that you'll replace the good archives by bad ones.
- In the Desktop Properties notebook, Archive page,
enable "Create archive at each system startup".
- Shut down the system, then re-boot.
- Go back and
disable "Create archive at each system startup".
Alternative: there's some software around that lets you create
archives in a more direct way, but I haven't tested it.
- The default initial size of the swap file is far too low.
My CONFIG.SYS has
SWAPPATH=E:\ 2048 24576
Different values might work better for you, but in all
cases that last number should be fairly large.
- When you boot OS/2, the system normally restarts programs
that were active the last time the system was shut down. Although
this can be a useful feature, it can cause trouble when crashed but unkillable
programs keep coming back. There are at least three ways around the
- You might like to experiment with the value of BUFFERS in CONFIG.SYS.
Increasing the value takes some memory from applications, but that's
a small price to pay for improved disk buffering. Suggested value: 100.
Note: this assumes that you have one or more FAT partitions.
If you use HPFS exclusively, and you're not too worried
about the speed of floppy operations, then you can set BUFFERS
as low as 3.
- Running CACHE.EXE from CONFIG.SYS can cause problems for some
(although not all) people.
Run it from STARTUP.CMD instead. (If you don't already
have a STARTUP.CMD, create this file in the root directory
of your boot partition.)
The best parameter values for CACHE.EXE depend on your usage
patterns and application mix, so it's not easy to give
hard-and-fast rules. As an indication, however, here's what
I have in my STARTUP.CMD:
DETACH E:\OS2\CACHE.EXE /MAXAGE:7500 /DISKIDLE:1000 /BUFFERIDLE:10000
Note 1: this affects only HPFS cacheing, you don't need
CACHE.EXE in a FAT-only system. (But I imagine that there
aren't many FAT-only systems left out there, now that most
people realise the limitations of FAT.)
Note 2: the on-line help for CACHE says that DISKIDLE
must be greater than BUFFERIDLE. You should ignore
this, it's a documentation error. For most people DISKIDLE
should be a lot smaller than BUFFERIDLE.
- In your PATH, DPATH, and LIBPATH, remove references to any
nonexistent or unneeded directories, and try to order the entries such that
the most-used directories are near the beginning. (In the case of LIBPATH,
the first entry should be ".") Note that many inconsiderate application
installation routines try to jump the queue by putting their own
additions at the beginning of the path; these are usually good
candidates for moving to the end. (If the developers are so sloppy,
it's probably software that you won't want to run very often.)
Remark: some programs don't like their directories to appear after the
512th position in the path. (But you'd be crazy to let it get that long
in the first place.)
Speeding up desktop operations
- The default folder view is the slowest possible choice.
To open folders faster, go to the Icon View page of
the folder's Properties notebook, and changed "As placed"
to something else - I suggest "Multiple columns". (I also
prefer to enable the "Always maintain sort order" option,
but that's just a personal preference.) If you don't
particularly need the icons - because, for example,
everything in that folder has the same icon anyway -
then change the Icon display to "Small size" or
"Invisible", depending on your own preferences.
To make these changes stick for all new folders,
make the changes in the Folder template.
- This next point isn't a speed issue, but now that I
think of it: lots of people don't know how to change
the default view of a folder. The way to do it is to
go to the Menu page in the Properties notebook,
click on "~Open as", then click on "Properties", and
then change the "Default action" field. Note: changing
the default will also change the default for any
new subfolders of this folder, but you can always go
back (if you wish) and change the Properties of the
- There's no reason that I can see for having both
"Folder" and "New folder" on your "Create another"
menu choices. Go to your "Programs" folder, open
the Properties of "New folder", and remove the
"Template" check mark. (Alternatively, if there's
a second folder type that you'd like to have - e.g.
a modified folder called a "Cabinet" - then rename
"New folder" and change its properties appropriately.
But any such template really belongs in your Templates
subfolder - I suspect that somebody forgot to delete
it from "Programs" before preparing the distribution
version of Warp 4.)
- Bitmaps as folder backgrounds are OK if you like
that sort of thing (e.g. I use them in folders that
I create for my children), but they do have some
effect on performance. To improve performance,
open the desktop Properties notebook, go to the
Background page, and select "Color only". Change
the colour to something you like. (If you have 256
colours or fewer, then I suggest that you choose the
"Solid color", even though this limits your choices.)
Once you've settled on your preferred colour combinations,
you can go to the scheme palette and set up your own
scheme. Hint: for the icon text background, one of the
options permitted is "Transparent color".
- You can improve performance by disabling folder
animation (System Setup/System/Window) and disabling system
sounds (System Setup/Sound/Sound). There's also a
slight advantage in setting System Setup/System/Logo
- You don't really need all those schemes in the Scheme
Palette, and they use up quite a few INI file entries.
Unfortunately I haven't yet worked out how to delete
the unwanted schemes. (If you delete them, they
somehow manage to re-create themselves.) Suggestions, anyone?
- The Warpguide cue cards are probably helpful for
beginners, but for the rest of us they're a nuisance.
To disable them, open Assistance Centre/WarpGuide/Properties,
and turn off the "Assist me ..." checkbox.
For a more complete removal, "Selective Uninstall" will let you uninstall
- (This next one doesn't have a big effect on performance,
so it's optional.) In the System Setup/System notebook, I suggest the
- Confirmations page: turn off most of the check marks, and
retain only those for which a mistake would be serious.
- User interface page: turn off VIO mouse actions, and turn
on Asynchronous Focus Change. (And
do not enable Full Window Dragging unless you
have a fast processor.) Warning: if you need copy-and-paste
to work in command windows, then you might need to keep
VIO mouse actions enabled.
- Print Screen page: Disable, unless you really need it.
- The on-line registration apparently works for some people,
but is a nuisance for many. To get rid of it, go to
OS2\INSTALL\Installed Features and open the "Inventory"
object. From this you can uninstall "Art" and be rid
of the dancing elephant forever. Of course you should
also choose "Remove this window" the next time
you get the "Welcome to OS/2" time-waster.
- If you don't use VoiceType - e.g. because you tried it
and discovered that your processor was too slow - you
should deinstall it, because it has some overhead even when
it's not in use. You can remove it either with "Selective
Deinstall", or via OS2\INSTALL\Installed Features\Inventory.
After the removal you'll have to manually edit CONFIG.SYS to remove
a nonexistent directory from the HELP path, and run CheckINI to
remove the registered classes that the de-installer forgot to
- A sparsely populated desktop behaves better than one
covered in icons. Move all your icons into folders,
keep as few folders as possible on the desktop, and
rely on either the WarpCenter or PC/2 to get at the
things you've put in the folders.
- Video drivers have a major influence on desktop performance,
so in principle you should upgrade (where possible) to the latest
version for your hardware. The catches are that (a) there are so many
video cards out there that nobody, to my knowledge, has managed
to coordinate the information about which upgrades are worth getting;
and (b) the drivers produced by video card manufacturers are
frequently buggy, and inferior to the drivers that came with your
OS/2 CD-ROM. Experiment with this if you're brave, but be prepared
to back up to the original drivers.
- You're probably not prepared to change your screen resolution - since
for most us readability is more important than speed - but you might
consider experimenting with the number of colours. As a general rule,
256-colour modes will be the fastest, 32K or 64K colours give an overhead
that might or might not be acceptable, and 24-bit colour is likely to slow
things down quite a bit. The precise trade-offs, however, vary a fair bit
between video cards.
Most of the items in this section apply only to those people who
have IBM1S506.ADD in their CONFIG.SYS. This is the driver for
IDE and similar drives. I'd love to have something similar for
SCSI drives, but so far I don't have much good advice for SCSI users.
There's just one note at the end of this section that applies
to SCSI drives.
Here's an example of a CONFIG.SYS line where both these options
are turned off, for a hardware configuration where there's a
single disk adapter (controller number 0) that is controlling two
hard drives (unit 0 and unit 1).
- My disk operations seem to have gone a little faster since I replaced
IBM1S506 by the PIIXIDE driver. (Look for piixos2.zip in
system/drivers/storage at Hobbes.) Warning: it's less generic than
IBM1S506, so might not work on your hardware. Be prepared to
back out again if it prevents your system from booting properly.
- There may be a bug in the bus-mastering option (which is disabled
by default in some OS/2 versions, and enabled by default in
others. It depends on things like which fixpack level you're up to). The
symptom is that, periodically, the disk becomes busy for no apparent
this ties up the processor to the point where user input is blocked
for several seconds. According to some reports, this problem
can be solved by adding the
/!BM parameter to the IBM1S506 line in CONFIG.SYS. My own
experience: I've experienced this problem intermittently, but my
testing so far has been insufficient to say whether or not the
/!BM option makes a difference.
- The IBM1S506 driver also has a "set multiple support"
option, which is enabled by default in Warp 4, and also in
Warp 3 with fixpack 26 or later. This option seems to
interfere with time-critical operations like serial input.
You can turn it off with the /!SMS switch.
BASEDEV=IBM1S506.ADD /A:0 /!BM /U:0 /!SMS /U:1 /!SMS
Note that you must specify which adapter and which unit(s)
you want the options to apply to. For further details type HELP IBM1S506.
You might need to experiment a little to work out whether it's better
to enable or disable either of these features, it probably depends on your
precise hardware configuration.
Remark: My own experience tends to suggests that there's some
deeper problem here: something in the file system is effectively
preventing multitasking which a disk operation is in progress.
The above measures reduce the impact of the problem but don't
really get at the root cause, which is (I believe) some sort of
design error inside OS/2.
My reason for believing this is that the WPS also goes "dead"
when a SCSI operation is in progress, or when you copy a file
to or from a floppy disk. (This last case is particularly noticeable.)
This did not happen in Warp 3 - there's something
new in Warp 4 that makes the file system a processor hog.
Leonard Pennock (firstname.lastname@example.org) has done some tests,
on an HPFS/SCSI system, that tend to suggest that the slowdowns can
be cured by turning off lazy writes. This didn't give any
improvement on my system; but it's something
you can easily try on your own system, to see whether it
makes a difference. (The appropriate command is "CACHE -Lazy:OFF".
You don't have to re-boot to do this.) If it does help, it could mean that there is a
bug in the implementation of HPFS lazy writing. I'd be interested
to get feedback on whether this works for other people.
- To get a more responsive mouse in a Windows program: open the WINOS2
properties (on the Session page of the Properties notebook), increase
IDLE_SECONDS slightly, and change
IDLE_SENSITIVITY to approximately 95. Note: many people will tell
you to change this setting to 100, but in my opinion that's a bad choice.
It will make that particular application hog the processor, at the expense
of everything else that's running.
- If you've installed Fixpack 1 and/or Netscape, you probably
have a corrupted SEAMLESS.DLL, and this can cause Windows
applications to misbehave. (Typical symptom: you can run a
Windows application once, but the system locks up on a second
attempt.) You can restore the original SEAMLESS.DLL from
CD-ROM as follows:
- Shut down OS/2, reboot it and type Alt/F1 when the white
square appears at the top left of your screen. When you get the
list of options, type F2 to start a command-line session.
- Type the following command, where F: is your CD-ROM drive.
UNPACK F:\OS2IMAGE\DISK_5\BUNDLE /N:SEAMLESS.DLL
- Before installing any Windows application, delete all files in
\OS2\MDOS\WINOS2\TEMP. (This directory is normally supposed to be
empty, but sometimes the programs that use it don't clean up properly.)
If you have multiple operating systems installed, you'll also need to clean
out the contents of any other TEMP or TMP directory that exists on your
system and that might be used by some version of Windows. Rubbish left
in the temporary directories can, for some mysterious reason, cause an
installation to set up incorrect options. (One very common symptom is
that the application tells you that it can't run SHARE.EXE - even though
SHARE.EXE is never needed under WinOS2.)
To change WarpCenter features, use a right mouse click
on the WarpCenter object in the OS/2 System folder, and choose Properties.
- The WarpCenter can prevent your system from booting up
properly (which is one reason why you should keep an
archived desktop). The problem is timing-dependent,
therefore it can show up after minor changes to a
previously working system. There are two different ways
in which I've seen the problem manifest itself:
The remedy is to remove WARPCENTER from the AUTOSTART line
in CONFIG.SYS. With luck you'll still be able to start
the WarpCenter from the Startup folder, but you'll have
to experiment a little: the results depend on the order
in which the WarpCenter is started up.
- The system locks up completely just as the desktop
is appearing on the screen (so that, typically, you
get a screen containing nothing but the desktop background); or
- There's an error message, as the WarpCenter is starting
up, that the CD-ROM drive is not ready, and then there
are missing entries in the Window List.
The safest course is to wait until all disk activity has
died down, and then start the WarpCenter from the desktop.
Fixpack 1 seems (with my limited testing so far) to have solved
Problem 1, but it doesn't help with Problem 2.
- On the WarpCenter/Properties/Monitors page, disable
the system activity and disk space monitors. I can't prove that
these are buggy, but I have my suspicions. Remark: experimentation
tends to suggest that monitoring continues even with this
option turned off, so I'm not totally sure that this recommendation
does any good.
- I've seen reports that the WarpCenter works better if you
change the Display page settings to put the WarpCenter at
the bottom of the screen, and enable it only when the mouse
is above it. I haven't noticed myself that this gives any
improvement - I think it depends on what video card you have -
but you might like to try it.
- If you have a Drives object in the WarpCenter, it will be
very slow to open because of access to removable media.
I suggest that you create a "Hard drives" folder in your
OS/2 System folder; put shadows of the hard drives in this
new folder; and drag that to the WarpCenter. Similarly,
create a "Removable drives" folder. You can then delete
the original Drives object from the WarpCenter.
- If you want lots of WarpCenter objects, add extra trays.
Note that you can cycle through the trays by clicking on
the blank space that's reserved for adding new objects.
- Try adding one or more of the following to your CONFIG.SYS:
The first of these allows you to kill misbehaving programs with a
Ctrl/left click on the WarpCenter task list (second button from the left).
The second replaces
the almost-useless "Find objects" by a faster and more useful program.
The third changes the appearance of the WarpCenter clock.
Deregistering unwanted classes
The concept of a "registered class" is fairly vital to the
way OS/2 works, and most registered classes should stay
registered. Unfortunately some such classes seem to slow
the system down a fair bit, so it's worth getting rid of
the ones you'll never use.
There are several alternative tools for deregistration.
The one I recommend may be found in the archives as
Removing unnecessary files
Normally I don't physically delete unneeded files, in case
I should change my mind later. (If you do delete any, keep track of
which ones they were, so that you can restore them from CD-ROM if
necessary.) Regardless of whether you keep these files, it's worth
cleaning the rubbish out of CONFIG.SYS.
- If your only internet connection is via a modem, then you
can comment out (or delete) the following lines from CONFIG.SYS.
REM DEVICE=C:\IBMCOM\LANMSGDD.OS2 /I:C:\IBMCOM /S
REM DEVICE=C:\IBMCOM\PROTMAN.OS2 /I:C:\IBMCOM
REM CALL=C:\OS2\CMD.EXE /Q /C C:\MPTN\BIN\MPTSTART.CMD >NUL
- Now that OS/2 is no longer distributed on floppies, it's
unlikely that you'll have any more use for XD-formatted disks.
You can remove the XDFLOPPY device driver with
(If you need that driver back, just take out the REM again.)
- If you've installed the Application Sampler, you have an
extra device driver (SDCS) that doesn't get used for
anything except Showcase. Once you finished browsing
through the CD, run "Remove" in the Application Sampler
folder. (You can always reinstall it later if you need to.)
- If you don't run DOS/Windows TCP/IP programs, then you can remove
the DOS TCP/IP support. The relevant lines in CONFIG.SYS are:
- The "Create Utility Diskettes" operation appears to be
buggy. To solve the problem, ensure that the first disk already
contains one or more unwanted files - this will cause a reformat,
after which the disks will be created correctly.
- Many people have complained that they can't work out
how to override the default associations for image files.
This is a known bug in Warp 4. (Correction:
a known feature. Only the users call it a bug.)
A fix for this problem is available at
- Here's a fast copy-and-paste technique that is not well
documented. Drag with the left mouse button
depressed to highlight the text to be copied. While the
left button is still down, click on the right mouse button.
Now go to the destination (which might be in another application).
Press the right mouse button at the insertion point. While the
right button is still down, click on the left mouse button.
Dealing with a noisy phone line
This topic has generated so much discussion that it deserves a
section of its own. This section will interest you if you use a
modem, and you get a lot of "[NETW] Invalid FCS" error messages.
Any phone line has a certain amount of line noise, so you can
expect an error like this now and then. (The software requests
a retransmission when it detects the error, so you haven't lost
anything except a bit of speed.) But if you're getting many such
errors, you have a problem - especially when the connection
degenerates to a "lost carrier" condition, at which point you've
lost your connection.
There are actually several likely causes of modem data corruption:
Unfortunately the symptoms of all these problems are similar, so it
can be hard to pin down exactly why you're having trouble. The tips
below might or might not help you; all I can suggest is that you try
them one at a time, to see which (if any) change gives an improvement.
- Line noise and signal distortion. This might be the
result of poor house wiring (do you lose your connection each time
the refrigerator turns on?), but it's much more likely to be
something in the telephone system over which you have no
- A poor-quality modem. Some modems are better than others
at extracting the signal from the noise. Most present-day
modems should be OK, but you have a right to be suspicious
of something you picked up for almost nothing at a garage sale.
- A misconfigured modem. Many of us don't have the patience
to figure out all of the details in the modem initialisation
string - most likely we just copied the string from someone
else, without checking it. Still, it wouldn't hurt to go
through your modem manual, to see whether you're using
parameter settings that aren't a good choice for the model
that you're using.
- Problems at the server end. If you used to have a good
connection, but it's now markedly degraded, a very likely
cause is an equipment fault in the server, or data loss
due to an overloaded server. You can suspect this cause if
many other users noticed the degradation at about the same
time. If that's the case, get the service provider to fix
the problem, or switch to another provider.
- Timing problems at your end. No matter how
good your operating system, or how fast your hardware,
there eventually comes a point where you're asking it to
do too much, and it loses data because it can't keep up.
Sometimes this is because you're running too many
concurrent applications. Sometimes it's because your
processor is too slow. Sometimes it's because interrupts
are disabled for too long (typically because of slow
disk operations). On older computers, it can be because
the serial port controller has inadequate buffering.
In all such cases, you might be able to improve performance
by reducing the speed of modem data transfer.
- I include the parameter setting S10=255 in my modem initialisation
string, to make the modem ignore brief losses of carrier. This can
help, assuming that your modem supports this option, in the case
where the line is subject to occasional short-duration losses of
- Making the COM port speed (page 4 on the settings notebook) too
high can be counterproductive; if the software can't keep up, data
gets lost. For most people, the best value is 57600, but a lower
value sometimes gives better results.
- Suggestion from Leon Kiriliuk (which also works for me): If you
have a slow processor, and you have Warp 4 or Warp 3 with
fixpack 26 or later, and you are getting an excessive
error rate on modem transfers, then you might need the /!SMS
option in the IBM1S506.ADD disk driver. See the earlier
"Disk drivers" section for details.
- Jarmo Paavilainen reduced his modem error rate with the command
MODE.COM COM1 57600,N,8,1,TO=ON,IDSR=ON,ODSR=ON,RTS=TOG
Neither of us can explain why this should help.
- From Brian Juergensmeyer: If your line noise is really bad,
to the point where
outgoing traffic rarely succeeds, try reducing the MTU (SLIP)
or MRU (PPP) to a very low value, e.g. 296. (The value is on
page 2 of the "Dial other providers" notebook.) If this helps,
experiment with smaller or larger values until you've found a
Other sites with tuning and setup tips
This automatic registration service comes courtesy of NetMind's
This information was compiled by
Please send complaints, criticisms, praise, corrections, suggestions, etc. to
peter at ee.newcastle.edu.au
Last modified: 23 July 2004