In case you still haven't flown yet...
The priority security line for TAP at EWR is only really semi-priority. It gets you to the head of the line to have your boarding pass and ID checked by TSA, but then there can still be a fairly decent line after that to go through the actual security check.
And if you show up too early before your flight (eg around the time the lounge opens), the priority security line won't be open yet. But then again, the regular security line shouldn't be crowded at that point.