There are many possibilities to tune Eclipse.
First, when Eclipse is hanging up you should start Eclipse with some arguments and give it more memory. Use: eclipse -vmargs -Xms256m -Xmx1024m or even more.
EDIT: "eclipse -vmargs -Xms256m -Xmx1024m" is the commandline command with which you can start Eclipse (well, depending on your OS). For that you either need to have eclipse in your environement path or you will have to use an absolute path to your eclipse executable file. Under Windows systems you may use for example "C:\Programme\eclipse\eclipse.exe -vmargs -Xms256m -Xmx1024m". You could f.e. create a short-cut with this command.
Second: If possible you can use several workspaces for your eclipse projects if they are not connected to each other. When using other projects than the ones located in your actual workspace switch the workspace to the one you desire. That way eclipse does not need to load all contents at startup and will therefor start much faster.
Third: You can disable the "build workspace" Option. Go to "project" --> and uncheck "build automatically".