After installing Lion my mac became super slow After installing Lion, my macbook pro became unbelievably slow.. what could be the reason?

Safari sometimes freeze for 30 seconds (in particular when there's Flash content). When I open mail after long time, the interface takes a while before to load.

Also Xcode and the simulator are slower.

UPDATE
So this how the system activity looks like when the mac slows down (even the dock bar is not responsive). I need to wait 2 minutes then everything starts to work again as before.

http://cl.ly/9ccS

http://cl.ly/9atU

http://cl.ly/9cFk
Activity monitor is your friend in this case. Check CPU/RAM usage and look for apps/services using a lot of resources, also check how your hard disk is doing in terms of throughput.

I've seen machine's hard disks slow down or just fail after an OS upgrade/install. It's a pretty disk intensive operation and can finish off older disks that were on their way out. Consider that as a possibility - perform a backup as soon as possible if you don't already have a recent one.