[fastball]

As far as I can tell, anything Javascript heavy performs significantly worse on Quantum than on Chrome.

The benchmarks I've looked at seem to indicate that this shouldn't be the case, but I'm thinking maybe Google has put in some "real life application" optimizations for certain configurations that can't be measured easily with benchmarks? Maybe they've learned some lessons from Angular? Just spitballin' here.

Kinda like how Apple managed for a long time to make everything a lot more "buttery" than the competition, even though they usually pushed hardware with specs that aren't at the tippy top.

Additionally, I think whatever version of flash is bundled with Chrome is less CPU-inflaming than the actual current version of flash, as flash sites seem to perform worse on Quantum as well, and Quantum relies are your system-installed flash.

[lossolo]

There was an article some time ago by someone from Chrome/google in which you could read that they optimized for benchmarks before but benchmarks are not real world usage so they stopped and started to optimize for real world usage. They did it because they optimized for some benchmarks while making real world average usage less efficient. Benchmarks do not show real browser performance.

[fastball]

Ah, thanks for that, it seems you are spot on.

https://blog.chromium.org/2017/04/real-world-javascript-perf...

I actually just ran their "real-world" test (http://browserbench.org/Speedometer/), and the results were:

  Chrome 62: 39.6 ± 3.4 rpm
  Firefox 59: 27.0 ± 5.6 rpm

So there may definitely be something to this theory. Would be good to have a larger sample size though.