The IDE loads faster with fewer modules enabled. Disable the modules that you don't use. Enable them dynamically at runtime when you need them.
With NetBeans versions 3.x and 4.x invoke Tools | Options and open IDE Configuration | System | Modules nodes, select a module or a group of modules to disable and set Enabled property to False.
With NetBeans 5.x use Tools | Module Manager to display a dialog allowing you to configure modules.
Source: NetBeans User FAQ