Slow Macbook (late 2008 aluminum)

Logout and in again but instantly after login hold the Shift key, this prevents any Login Items from loading, is this better, if so look into your Login Items.

Or make a new User account, restart and login into the new one, if it is OK there your normal User Account has issues.

Also, open Activity monitor, see if you have loads of pageouts, also look if 1 process uses a lot of real memory.
If you don't know what to look for make a screenshot by holding Command-Shift-4, then hit spacebar and click window, post here, be sure to have all processes visible.

 

That seems to be fairly normal dependable on what you did.(Firefox)

Have you tried the other suggestions?

I know there sometimes is also a problem within the Byhost Folder in your preferences but I can't really remember which files to delete inside that folder, think it is the com.apple.SystemUi plist files but I am not sure.

 

Just curious: how much space do you have on your HD (SSD?) Getting too full really tends to slow things down.