Im sick of this .

[D0ctor]

Go to your game library, right click on Garry's Mod > Properties > Launch options and paste this there: -windowed -noborder

Although you will lose some performance, still it's worth if you must wait 5 minutes, with these commands you will be able to instantly switch between garry's mod and everything else.

I had the same problem until recently when a friend told me to do this ^ now my gmod open in about 2 or 3 seconds. Great advice again Freezak