I assume that you've installed your Java using the JRE offline installer.
To find out whether it is really LW that takes up all your resources, go to your Task Manager (crlt & alt + delete one time)>Processes (the tab next to Applications), then click two times on the CPU tab to bring up the processes that use most of your CPU.
Make sure that there are not two LW .exe or two java.exe running.
If that isn't the case then close LW, go to your desktop, right click your LW icon, go to properties and change the compatibility to either Windows 2000 or Windows NT. That might fix it.
Checking your whole system for any viruses, spywares or trojans wouldn't be wrong either.....
