Sweeping a form out from memory...

[aliinal]

I have to load and unload lot of forms in my program. (These are MDI Child forms generally. But can be normal form sometimes)
But i'm not sure if it's enough to unload form to sweep it out from memory...
example when i say
unload form1

all information about form1 is removed from memory???

I'm asking because i realised that after some loading and unloading procedure, system gets unstable and slow..

If anyone can help me i'll be happy
thanks.