okeyyy...but still you got pulseaudio hitting cpu and also alarmed using cpu? Also hildons-desktop taking cpu but that´s okey if it´s not also constantly taking that much.

Only processes taking constantly 1 or more % of cpu with idle N900 should be xorg.

In xterm:
killall pulseaudio

also what have you installed?
maemo-list-user-packages

Also i would recommend trying swappiness trick. Search forum for more information.