Hi,
Good question 
We have worked a lot with the program and the documentation hasn´t changed in the same pace.
$fps: is the frames per second from the source.
$pfps: is the processed frames per second from a source. For overlay etc. there is no need to process all frames coming from the source. It will only increase the cpu load.
$time has also changed and now we have $time, $time-eu and $time-us.
-Henrik