I have a Macbook white (2010) and I'm facing an annoying thing since I'd bought it.
I've already re-installed the system some times, but the fact is that I got short freezes for 2-3 seconds when saving common text files in all editors (TextEdit, MacVim, TextMate, Sublime Text 2). The system freezes and shows that color spinning ball. These freezes also occur in Terminal app, when I push the up arrow key to get the last command entered. Looks like the OS is trying to achieve something else while I'm typing, like a search for example.
I disabled the Spotlight, because I've read that it's what was causing the same issues for many users, but it didn't work for me.
Also, I checked the disk permissions, and made everything that has to be made (including fsck on single user mode), but the problem still continues. I installed Debian once, without any issues of this type.
My HD is a Western Digital 5400 320GB.
Someone having the same problems? I'm almost backing up all my stuff to go back to Linux... I'm very frustrated because I'm a programmer, and such a unresponsive system can drive you nuts when you're having intensive saving/testing debug routines.