When simulating, any Timer based interrupts seem to be quite random and often have large delays. I'm often waiting for the timer interrupt to overflow and trigger a part of the program.
At other times the interrupt Macro keeps triggering as i'm trying to step though a tricky bit of the program.
If these are a general problem that others also experiance, could a future feature allow you to manually trigger or stop a timer interrupt during simulation.
As ever, I remember the following from my support days "Requesting something is easy, implementing it is the hard bit"

J.