Speeding Up Mail really works!
There's been a lot of posting about speeding up Mail.app by rebuilding its envelope index recently. Until now, I didn't jump the bandwagon, because I've heard of such tricks numerous times that turned out to be placebos.
Then, recently at work, Mail.app refused to find any results using Spotlight. So I remembered all these tricks and thought I'd try whether that fixes my Spotlight searches. And what do you know, it did. Mail had been very slow to launch and switch between folders (especially switching to the Inbox or other folders that aggregate contents of their sub-mailboxes), and that was also faster now.
So, if you have problems searching in Mail.app, or it's just generally abysmally slow, you may wanna give this a try. Obviously, this won't make your hard disk faster or keep your Mac from swapping if you have too little RAM (and it seems like less than 1GB is already too little these days), but maybe it'll just slightly speed up things.
Oh, just in case the link breaks, here's how to rebuild your mail index using Terminal.app:
% cd ~/Library/Mail/
% sqlite3 Envelope\ Index
SQLite version 3.1.3
Enter ".help" for instructions
sqlite> vacuum subjects;
(That "^D" is what you get when you type Ctrl-D, which is how you close sqlite once it's finished rebuilding the index)