My Eclipse was getting slower and slower over time. Tips I found on the Internet did not help. What I did is completely deleted my workspace, created new one and reimported all
Eclipse is programmed as a filebomb, and it causes a large variety of problem, evben on modern robust filesystem. Problem can goes from large waste of diskspace for nothing to preventing your OS to boot if your workspace is on your OS partition. Eclipse is programmed as a filebomb.
The cleanup mechanism in eclipse doesn't work, so the only viable option is to frequently cleanup your workspace by hand at regular interval, or to add your cleanup code to a sh file that does it before launching eclipse.
An other option will be to introduce the eclipse developpers to the fabulous world of databases that produce faster to run and easier to write code. Sadly a rhumor says that they will shot on sight everyone that pronounce the words "sqlite" or "jdbc", and will sacrifice virgind every sunday to the all-mighty-god-of-filebombs.