whenever i fire up any of my trucks i always let them idle for 15 - 20 seconds and let the engine warm up a little bit. that is probably why you are experiencing slow performance gains. try letting your engine idle before you start beating on it.
Richen up the low speed needle and apply the brakes. The clutch is slowly grabbing the clutchbell.... It's not really a bad thing, just put the car down and dial in a tiny bit of off-throttle drag brake.