My N900 don’t seem to be responding as well as before.
Browser seems slower even on wifi.

Facebook for example I tap on profile to view my page and it just highlights it and I have to keep tapping the screen and eventually it loads, this problem I have come across on many other sites I visit on the N900.

Also exiting an app on the N900 is pissing me off, I have to tap the X button at least 3 times to exit.

Another problem but this was before the update. When I turn the phone off and want to turn it on again, I have to press the power button 3 or 4 times to turn on

Normally it should settle with reboot but you can run xterm and then top command and look if some program is taking all CPU.

Reboot + recalibration