When you say 'saving frames' are you saying that you are running the 'haste' calculation every single frame? That calculation should only ever need to be done whenever you complete an activity that alters haste.
I don't think that alt-tabbing is the issue as I don't recall alt tabbing before it happened. What happens is I manually swap the mode to 'single' by clicking it, and the symbol reflects that, however nodes still loop even though the symbol is displaying single (i was not using queueing either so that wouldn't do it).