Garry's Mod - Freezes when I type (read)

[Dynamite]

Hello Facepunch.

I play Garry's Mod nearly everyday and I play on the D3vine DarkRP.
When I press y to chat and such my game is normal, nothing is wrong. But when it's been about 3 hours my game decides to be mean and lag for 2 seconds when I press y, then when I press enter after typing my message, it lags again for 2 seconds.
So I have to close Garry's Mod then relaunch it, then it works again and theres no lag........until its been ABOUT 3 hours.

This sucks because it truly affects my gameplay on DarkRP considering I don't have a microphone.

So if you can help, that would be TRULY appreciated. Thank you.

EDIT: I have a feeling that -heapsize has to do with this