My DW and I just returned from MCO Sunday (11/17). We flew United out of terminal B. The lines at security were long -- they said they are always long and always VERY busy on Sundays. However, we got through security in about 5 mins. Heck, I didn't even have time to THINK about complaining about a wait!
The security there is done by federal employees (TSA). Don't be surprised when they say "Sir" or "Ma'am." They are actually quite friendly and very professional.
Be sure to take off anything metal (watches, bracelets, etc.). They will ask to x-ray any sweaters, jackets, coats. I usually take off my watch and take my wallet out. For some reason, my credit cards seem to set off the beeper (and the wands) -- maybe I have too many?!?!
Bottom line: I wouldn't worry too much. If you arrived 1 1/2 to 2 hours early you should be OK.