How do i make Gmod not lag???

Gmod laggs all the time even when i dont have any addons.
The game also freezes for almost minuttes if i make 2 props at the same time.
my specs:
Windows 7 Ulitmate 64 Bit
8 Gb ram
Nvidia Geforce 9600 GT
AMD Atholn™ 64 X2 Dual Core Processor 4200+ 2.20 GHz

Update your drivers.

try doing a disk defrag. That will speed it up a little. Updating your drivers will also make your performance better. If you don’t have a defragger use this: http://download.cnet.com/Smart-Defrag/3000-2094_4-10759533.html?tag=mncol