Reading your post the vision off a train with people overloaded flashed in my head. Is 135 a big load for the type of aircraft... I wonder.
Well, the 737-300's that the airline I worked for had 123 in coach and 8 in first, so, it sounds like a full flight, most likely no FC, and about 148 or so seats packed in. Charters tend to have more seats than scheduled airliners. I don't think this is like the flight from Benin that was, I believe, seriously overgrossed with too many people. That plane had too many people, old crappy plane, and short runway and a hot day.
As for this flight, word is that it was foggy on takeoff, but I doubt it was overgrossed. Sharm has a long enough runway for 767, 747, A340 planes. Usually with crashes you find that there are several little factors that all add up to danger, remove one factor and there wouldn't be a crash.
"Reading your post the vision off a train with people overloaded flashed in my head. Is 135 a big load for the type of aircraft... I wonder."
No, that is about average for 737.