Gmail's so bad now that I only use "classic HTML" Gmail in the browser, and native clients (Apple's Mail, for example). I have no idea how they managed to make a relatively simple "web app" so huge and heavy. You could add all of full-fat Gmail's features to "classic HTML" Gmail for very little cost in bundle size and active resource use—though the result might not be an "app" in many folks' opinions, I guess. I just know navigating classic Gmail, with its "bad" full-page loads, is way faster than the "efficient" AJAX-style crap on normal Gmail.

Mobile Gmail's not just heavy—it's broken. Whatever stupid, misguided bullshit they're doing with scrolling makes it register clicks where they weren't intended if I'm not super careful.