My n900 had started to slow down considerably so I decided to cut the number of pages I was using: from 4 to 2.
I had a whole page just for bookmarks so it wasnt that hard.

I also ununstalled all the apps I was using rarely or near never, you know, in order to clear out the rootsh.
I then decided to stop using widgets than needed the internet such as the weather ones and the IP ones (the last ones are real cpu hoggers!).

Now the n900 is very snappy and responsive. Did I mention the battery is lasting SO much longer?