This might sound odd...
I think working in the wp-admin area of my WordPress sites in Firefox activates my computer fan. Sometimes Firefox will seize after I click to upgrade a plugin or after I click on a tab and other admin actions. The spinning browser activity indicator will freeze in motion, the computer starts to sound like a helicopter, and I have to sit (for two minutes typically) until Firefox become unstuck.
My workflow includes opening a couple tabs for different sites I maintain for clients and reviewing latest stats, posts, and comments each morning. I'll click something in one tab then switch to another tab while the previous one is thinking or loading a page. Sometimes I'll have four or five tabs going - each loading different wp-admin areas of different sites.
The performance degradation also happens when viewing just one site as well. After logging out or closing the wp-admin tab for a site the computer fan will become less and less noisy like it's calming down.
I've recently upgraded my hosting service to a private server so I have dedicated mysql and cpu resources so that shouldn't be an issue. My internet connection is over high speed Comcast cable and I've had the cable guy come do speed tests to verify my service is okay and the cable wires aren't noisy. I've also installed Google Gears and using Turbo. But my G4 PowerBook still sounds like a helicopter at times when working in wp-admin.
Anyone else have similar experiences?