We have three Sitebuilder servers, all running SB 2.1.3 on CentOS 4.4 Linux. All of the machine hardware is identical on all three servers. They are IBM X336 servers with single 3GHz Xeon processors, 4GB of RAM, and a pair of 10,000 RPM Ultra320 SCSI drives in a RAID1 configuration. Customer websites and the sitebuilder admin panel come up very quickly. But if a customer wants to modify their site, it takes over 90 seconds to move from one page of the wizard to the next. Same with the admin panel... I can search for a customer and get the record very very quickly, but once I attempt to move from section to section administering that customer, I have 90 second pauses between section loads. Our servers are fairly heavily loaded, two of them have approximately 15,000 users, one has about 4,000. The strange thing is, this lousy performance doesn't seem much different on the 4,000 user machine than on the 15,000 user machines. What is the best way to increase performance on a Unix / Linux Sitebuilder server?