It's really not too bad. I never check bags and I have TSA Pre, but even the regular line seems to move at a decent rate. I also fly United 99% of the time, which means I'm almost always going out of Terminal C. I've flown three times this year (once internationally to London) and have zipped through security (10 mins from entering the airport to getting to the gates). Five hours early is definitely overkill.

The big issue I have with EWR is food service. If you're planning to eat at the airport, even if it's a food court meal, leave yourself plenty of time as their operations are horrible. Like 45 mins for a food court pizza horrible. It's also overpriced as hell, more so than other international airports its size — so bear that in mind.