Wonder why Mega has issues with Firefox. Any download bigger than a 1GB it wants to use mega plugin.. but on Chrome, it is fine downloading through browser, doesn't matter the size.
Because Google implemented the functions from the mega extension in the browser and Mozilla didn't - considering the MEGA/Google implementation I'd have to say - stay away from them if you use an SSD disk and even if you don't better use an external download manager than Chrome or the FireFox add-on.
P.S. It's a limitation imposed by the technology MEGA decided to use and not a browser thing.
I just bit the bullet and got the mega plugin since I only use Firefox and have since I was 13 and my mom found my search history on IE. Figured a second browser exclusively for me meant I didn't have to remember to clear my history and it worked.
Might want to consider using chrome portable just for mega stuff.
I wouldn't recommend using mega plugin with firefox if firefox is your day to day browser... just be sure to read their privacy policy and see if you are comfortable with it.