OS/2 FAQ List: User's Edition (4 Apr 94)

(5.6) Performance Tuning

How do I tweak OS/2 2.1 for maximum performance?

For OS/2 overall, the CONFIG.SYS parameters MAXWAIT, TIMESLICE, PRIORITY, 
PRIORITY_DISK_IO, PROTECTONLY, and cache settings (in the DISKCACHE line, 
for FAT; or IFS line, for HPFS) can be tweaked.  The swap file should be 
placed on the most used partition on the least used hard disk, and its 
location is controlled by the SWAPPATH line.  See the online Command 
Reference for details.

FAT partitions should be periodically defragmented.  A shareware 
defragmenter for DOS called DOG (Disk OrGanizer) works well, as do many 
others.  (You can boot DOS from a floppy disk to run such a utility.)

For the Workplace Shell, drag shadows of most often used items to the 
desktop or to folders closer to the "surface" -- opening folders takes 
time.  Drag shadows of program objects you use often (e.g. the Win-OS/2 
full screen Program Manager) to the Startup folder.  Disable animation (go 
to OS/2 System -> System Setup -> System -> Window).  Use the faster 
Details View when opening drive and folder objects; to set Details View as 
the default, open the settings notebook for the object, select the Menu 
tab, click on ˜Open, then the Settings button, then select the Default 
Action.

Try reducing the number of on screen colors or dropping down in screen 
resolution to enhance speed.  Close (not just minimize; check the Window 
List) unnecessary objects and applications.  Use the Monochrome scheme 
from the Scheme Palette -- it provides marginally faster screen updates. 
 Consider adding more RAM.

For DOS programs, run full screen instead of windowed if speed is 
important.  In DOS Settings for each application: reduce conventional, 
XMS, DPMI, and EMS memory allocations to the bare minimums required for 
maximum performance; turn off VIDEO_RETRACE_EMULATION unless necessary; 
adjust IDLE_SENSITIVITY; turn off DOS_BACKGROUND_EXECUTION if not needed; 
change the HW_TIMER setting (particularly for games); enable 
VIDEO_FASTPASTE if possible; turn on HW_ROM_TO_RAM.  Communications 
programs should use hardware handshaking where possible (use OS/2's MODE 
COMx command if necessary), and a buffered UART can prove helpful.  (DOS 
programs running under OS/2 will not be aware of a buffered 16550AF UART. 
 OS/2 virtualizes the serial port and manages the buffer itself.)  For 
faster printing set the DOS program's output port to LPTx.OS2 (where x is 
the printer port number) -- use a "print to file" option if necessary. 
 Disable any DOS print spoolers; rely on OS/2's spooler instead.  Increase 
CONFIG.SYS's PRINTMONBUFSIZE values.  Other, standard steps to enhance DOS 
performance (e.g. increasing BUFFERS in CONFIG.SYS) of course apply.

For Windows programs, run using a full screen desktop if speed is vital. 
 The Win-OS/2 Full Screen icon set up by the installation program has poor 
Settings.  For better performance perform some of the same steps outlined 
in the preceding paragraph, including VIDEO_RETRACE_EMULATION off.  The 
same printer output advice also applies.  Consider disabling the Public 
setting in the Clipboard.  If available, set VIDEO_8514A_XGA_IOTRAP to 
off.  If mouse control is lost when switching to/from the Win-OS/2 
session, try setting VIDEO_SWITCH_NOTIFICATION off.

Related information:

(1.3) DOS and Windows Compatibility 
(5.7) Measuring Performance and Memory Usage

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