Posted by Wesley Tanaka on March 8, 2009 at 6:48am
I have created a low memory version of system.module for Drupal 6.10 which can be found here. I found it gave a modest performance improvement with low load performance testing on my development machine. Where it shines is under high load relative to tight memory conditions.
With ab -c 100 -n 1000 http://example.com/user on a real site, applying this patch gave somewhere between 18 and 40% reduction in average time per request.