When I had to use gmail for work I switched back to the plain html interface. It was startlingly fast
As far as I could see all the complicated front-end stuff added zero to the user experience. Ok, so yeah, you needed a page load to view a message or whatever, but it was quick and hardly noticeable. All they needed to do was freshen up the stylesheet and call it a day. But, I guess, all those developers and product managers needed something to do in between building a new messaging app and killing the previous one.
Google lost a ton of good will by making Gmail a laughably bad experience on load.