Yes, but these changes take time and they only started working on them when users started leaving for Chrome. Like many others, I used Firefox for a long time

Yes, but these changes take time and they only started working on them when users started leaving for Chrome. Like many others, I used Firefox for a long time despite it being technically inferior to Chrome, but at some point you say 'fuck it' and make the change. Mozilla, given their market share, should have been first to offer 64-bit support, separate processes for tabs, sand-boxing and a lot of other stuff, but they've been asleep, because for a long time there was no strong competitor.