SPR# BHUY75XJL2 - LotusScript is yielding too often, which was necessary a while back with slower machines. Now that Machines are much faster, we changed it to yield less often.
However 8.0.2 also introduced this fix:
SPR# DCOE6KPW48 - Fixed a crash calling fulltrim on arrays returned from certain other lotusscript builtin functions (eg Join).
Unfortunately this fix could cause your Lotusscript your code to run slower if you used dynamic arrays or lists. Possibly much slower - on the order of over 3-4 times as slow, even with the first fix running also.
During the 8.5.1 beta we noted this problem and worked with IBM. They stamped out a fix that made it into the gold 8.5.1 release. If you're not affected by the crash mentioned above (and most people won't be -- it's apparently an extreme corner case) then you can turn that fix off with this INI setting:
SPR# DPOL7PEHQX - The fix for SPR DCOE6KPW48 can cause a performance issue when heavy array processing is in use. This SPR provides a new ini - FullTrimFix=0 - to disable DCOE6KPW48, which then will restore performance.
The end result is that your script code on 8.5.1 will run significantly faster than any prior releases simply by upgrading and adding this INI setting. We're seeing around 30% in production. You may see even more. Don't forget to also do this on your servers that run script code agents.