Speedup NetBeans 6.5 startup in windows

To speedup NetBeans 6.5 startup in windows, go to etc folder under NetBeans installation folder [for example on my machine it is E:\Program Files\NetBeans 6.5 RC2\etc] and open netbeans.conf

Edit the value of Xms to 256m as in the screen shot below.

Another way to speed up NetBeans is to deactivate plugins. In NetBeans menu, go to Tools--> Plugins and deactivate unused plugins one by one. [Choose the option to restart IDE later if you have more plugins to deactivate]