one rom versus another

[piperthedj]

good morning all, my issue lies multi faceted, anyone who can help is appreciated.

OS stock 6.1

last week my htc6900 started having an error (unable to load something.exe) i wisely asked a friend who has a pro and he advised to hard reset. after hard reset everything is very slow, rather annoying, to a point if i have more than one program running, it boggs down. i thought there may have been a patch from my carrier i lost when i hard reset. i have called my carriers tech-data support and they say 'hard reset will bring unit to our latest rom, there are no patches'.
my question, i have read many posts on the various roms available. i am looking for something quick. something that does not bog down when i have over 5 programs running. is there such a rom?

additionally
i do most of my work on a MAC. is there a way to do roms with a mac? most of the roms i have looked at have an .exe

thanks in advance