I recently bought a MacBook Pro (2 GHz Intel Core i7 with 64-bit kernel and extensions enabled) to develop with Java. First thing to do was updating Java and installing Eclipse IDE, but everything about Eclipse was very slow.
So I started googling and found the solution here:
The problem was related to 64-bit, Java and Eclipse are ready for working on 64-bit but you have to configure them.
Then, open eclipse.ini and update of this way (lines updated are 12, 16, 19, 20 and 21):
[sourcecode language="text" gutter="true" wraplines="false" highlight="12,16,19,20,21"]