So to reduce freezing and stuttering on Dresden & London Commuter Ive discovered that by spawning on foot in Dresden/Victoria and taking over a service rather than starting in the train results in a far smoother experience on my PC set up. The problem is that all S1 services which arrive into Dresden when you enter the CAB the SIFA doesnt work either from the foot paddle, keyboard or Raildriver. Also you cant enter the coach from the doors closest to the CAB but the next door down.