There is a minor problem in the Memory Manager in the ROMs of the
Macintosh IIci, IIfx, IIsi, and LC. This results in performance
degradation in an extremely small number of applications, and doesn't
cause system crashes. This affects few applications and very few
customers. It is not a new problem and it only applies if you're using
System 6, System 7.0 corrects this bug.
During extensive testing and research, Apple investigated a variety of
solutions to enhance the memory manager performance. One solution was
software called the Memory Manager INIT ( a software "patch"). Testing
revealed that this patch did not enhance Memory Manager performance, and
introduced risks, such as decreased performance, in some mainstream
applications. We are aware of the distribution of an unofficial version
of the Memory Manager INIT. This INIT was modified from Apple's
experimental version, and should NOT be used. This INIT can cause data
corruption, data loss and system crashes. Apple strongly urges that you
throw away this INIT.
Because of the minimal impact, the Apple task force decided that it was
not necessary to develop, test, and release a patch to the Memory Manager
for System 6. It is important to realize the implications of patching the
Memory Manager. Since it is at the heart of everything the Macintosh
does, any patch would require major testing resources to cover the entire
product line, large numbers of applications, and Network and
Communications products.
Based on developer feedback, customer feedback, and extensive in-house
testing, Apple identified very few affected applications.
If you have a customer reporting slow downs on the Macintosh IIci, IIfx,
IIsi, or LC, check the following items:
1) They aren't using built-in video. The Macintosh IIci and IIsi
cycle-steal. The LC does not.
2) They have a clean System folder. Large numbers of INITS cause many
problems.
3) They don't have network-based problems that also cause slow downs.
4) They have a properly configured SCSI bus.
5) They generally have a configuration that works.
If the slow performance persists after checking these items, it may be due
to a Memory Manager software problem. The best solution would be to
upgrade to System 7.