Since when I’ve begun to code in Java (in 2005) I’ve tried many IDEs, but the best is still probably Eclipse. Sadly enough, it’s the best but not that good in every aspect. Sometimes you spend whole days trying to just make something work: while you’re doing everything right, he’s trolling you not really doing something at some point; so the hard part is finding out what it is and then doing it manually.
The issues and solutions I’m going to list apply to Indigo SR1, but probably to many other versions (from the beginning until the end of times, as we are used to with Eclipse). Solutions are mainly from other people, go see the linked threads and posts for credits. I just wanted to have them all in the same place.
as suggested here. In this way you’re clearing a cache for project metadata (has it errors? are all changes committed to the repository? and so on), and in order to regenerate it you have to close and reopen the project.
Be aware that even if you disabled the validator you can still have caching issues as described in 2).
4) In a Dynamic Web Project with many files (hundreds, both .java and .js), the time required to open for the first time (since Eclipse startup) the project tree is about 1 minute.