First:
flash anew and do not install battery/speed patch.
Second:
Nokia SSU and Apps repo??? They are gone! --> maemo-repos.com

The N900 is not known to be the fastest beast. But after a flash and fresh install it is not that bad.
What do you expect, to what compared, which specific task/software?


--
oh, and one more regarding extras-devel:
you know that this is only for peeps who can cope with a not working sW, strange reactions, borken device?
You should enable it only for specific installations or know exactly why you have it enabled.