Increase Eclipse's Memory Settings

eclipse.ini

-Xms40m 
-Xmx256m 
-XX:MaxPermSize=256m

Recommended settings for Android development:

-Xms128m 
-Xmx512m 
-XX:MaxPermSize=256m

These settings set Eclipse's minimum Java heap size to 128MB, set the maximum Java heap size to 512MB, and keep the maximum permanent generation size at the default of 256MB.

http://source.android.com/source/using-eclipse.html