Since a few days my Mac running 10.6.7 is ultra slow, it shows the beach ball very often and some apps doesn't open anymore. (for example iTunes and iMovie)
Does anyone know how to fix that? It is a little bit useless at the moment...
Download either Maintenance or Onyx and run all the cleaning routines. Let the cache cleaning program clean all the files and the program to reboot your Mac. Then upon that cache cleaning reboot manually reboot again to completely rebuild your Mac's startup/shutdown system cache.
This should help and cache cleaning like this IMHO should be run about one every three or four months to keep your OS X running clean.