One of the machines I use is an old Dell Latitude D620 (2006, Intel Core2 CPU T7200 2.00GHz[0]) on a debian base. I can tell you from personal experience, on this machine, that Mozilla's latest Quantum Browser is heads above Chrome and their "clones".
It is so quick to load (even loaded with extensions), it replaced Pale Moon as the default browser for this laptop. I was stunned at the performance improvements in Quantum. I remain surprised, every single day, that the modern web has been made available on a laptop that's 13 years old.
All other Chrome-like browsers (Chromium, Opera, Vivaldi, etc) take much longer to load, cause the cpu to throttle (fans kick in) which can lead to overheating and shutdown issues. They are essentially unusable on that machine. Firefox Quantum, otoh, is snappy on this machine.
I say this because I'm genuinely curious by the "too big" comment. I honestly find it puzzling (unless you're comparing a modern, full-featured browser to Dillo or Links2/GUI: both of which are favs of mine for their use cases).
I had turned my back on Firefox for a few years because of performance issues, caching problems. They didn't just correct these issues, they've done so in a way few software upgrades have ever managed to do in my experience (dating back three decades) and have blown past their competitors from a purely performance standpoint.
[0] https://www.cpubenchmark.net/cpu.php?cpu=Intel+Core2+Duo+T72...