In the new IDE version 1.5 there is still an open well known issue unresolved: an error in rxtxSerial.dll which causes very long (thirty seconds or so) delays on startup and whenever 'Tools' menu is open on any system that has bluetooth or other slow responding virtual COM ports.
The issue was widely discussed and was resolved in a topic:
however the changes (updated rxtxSerial.dll) posted there still in 2009 year to my suprise didn't find their way to a new version of IDE.
Please Arduino team - do include this patch in general release. Otherwise you have to replace the faulty dll after any new installation.
Thank's god the language problem had been fixed (in 1.0.1 you couldn't choose Polish language because it was making the IDE unusable - it didn't start). Now it works.