On OSX, Firefox and Google Drive work fine, but Gmail is a whole other kettle of fish. I don't know what UI change they implemented last year or so, but it is nearly unusable on Firefox, from absurdly long load times, to a 2-3 second wait for contextual options to appear when you right click.

Switched to ProtonMail's free tier and will gradually migrate everything there aside from newsletter and software beta signups. Those emails are mostly trash anyway.