I never lost to a 'slow' player. Slow players are using it as a 'move' to break the other players rhythm. The reason I never lost is that, my cue comes apart. No reason to let some guy 'move' on you when you're bettin your cash. No shot clocks in pool rooms, so, just unscrew. There was plenty of good action in the 60's & 70's. No reason to put up with 'slow' players, unless you're stealin!
ps
All thoses 'air strokes' players use now is just 'profiling'! Love to play thoses guys that do all that and then 'dogit'!
I never played slowly just to "break the other players rhythm", although I would sometimes use safeties to do that against fast players who hated safeties.
As I stated above, I played slowly because that was what worked for me. As I learned more about the game, and saw options more quickly, my game sped up, quite naturally.