I've heard quite a few anecdotal reports of FFQ being slow on certain websites. I've had no such issues, and in fact really like Quantum. I've used FF for a long, long time. I may be biased.
Edit: Had no slow-downs or hang ups on any of the mentioned sites (including the whatsapp linked below)
Edit: Had no slow-downs or hang ups on any of the mentioned sites (including the whatsapp linked below)