OS X Mountain Lion is INSANELY slow, laggy and "crashes" to login screen

[IT07]

hey all,

Since Mountain Lion all i got is problems. My iHack is VERY slow, laggy (especially sometimes while typing) and it's startup time is insanely slow too.
it takes about half a minute to shutdown, and about 20 seconds for the login screen to appear after the bootscreen with logo.
And today I had a really strange problem for the 1st time: I was editing some photos and while I switched to Safari that was on an other workspace
the transition between the two workspaces stopped and it froze. I saw a black bar that was about 50px wide between the two workspaces.
Then, the screen got a bit more white for a few seconds and then back again. immediately after that the login screen appeared.
So I logged in, and that took a **** load of time too. when finally on the desktop, applications where active that I was using before logging in but
clicking them did not result in immediately opening the application.

And that's the problem I have. Sorry if my description of the problem is not clear enough, english is not my native language

Thanks in advance.
grtz, IT07.

 

[eelhead]

Topic moved from OS X Support to General Help to give better exposure.