This mod will output message with an approximate tps figure to your default chat frame after you leave combat. It won't output a message if combat was less than 5 seconds, or if threat was less than 500.

Threat is total threat vs all allowed targets. For a target to be allowed, you must be in combat with it, and directly target the mob. If you don't target the mob, threat is no able to be collected on it.

Time in combat is total time, even if you stop attacking for 2 minutes, the timers still runs. In wws terms, this would be "battle time", not "dps time". Tps = time_in_combat / total_threat

Threat reductions(such as boss/mob aggro wipes) will be reflected in the tps displayed.

No threat calculations are done. All threat data comes directly from the game. Only time in combat is calculated, so this should work perfectly for all characters regardless of spec, class, talents, gear, buffs etc...