We have extensive leak checking in our testing for Firefox, so hopefully the JS engine is not "very leaky". One part of Quantum, which does not have anything t

We have extensive leak checking in our testing for Firefox, so hopefully the JS engine is not "very leaky". One part of Quantum, which does not have anything to do with Rust, is to figure out how we can spend less time running unimportant JS (like maybe in a background tab), which will hopefully reduce CPU usage.