I am having APC php accelerator and it has really helped me to increased the performance. My  server performance is increased by 250% to 300%.  You can try adding more RAM or clustering your webserver.

(Please note that the discussion has moved to https://moodle.org/mod/forum/discuss.php?d=216691. I also removed the link to the "chess" which has no connection to Moodle.
Edited by Visvanath Ratnaweera - original submission Wednesday, 19 December 2012, 9:05 AM)