I recently installed Mach3 and it definately runs motors smoother that Mach2. It does take some time getting it all debugged.
Since you are running on a laptop, be sure to plug it in to 110V power whenever using it for CNC control. I discovered this by accident. I had my router running well with Mach2, installed some G-code and then took the computer to the shop for a quick test run. It ran like crap. As I tryed to figure it out, the battey ran down so I plugged it in. Instantly, the controller started running the motors smoothly. Apparently, the system slows to conserve power when running on batteries. There are probably configuration settings in Windows to change this, but I've since changed to a dedicated desktop system for machine contol.