Garry's mod Lag Spike! And crashing!

[rocknexus]

Every time i spawn a new weapon, it lags up and freezes for a split second, -it does fire,- skips the firing sound, then goes back to normal. Also when i try to render icons, like getting a model from an addon, it crashes. its getting very annoying, and i would appreciate a solution. My specs are fine, all pass, i really do not know what is causing this.
Intel i5 2.5 GHZ
AMD Radeon HD 6750M 512 MB
4GB Memory 1333MHZ DDR3
OSX 10.8.5