Does anyone know how this compares to the current implementations of competing browsers? ie. is Firefox still playing catch up in some respects or is this leaps ahead of the competition too?
Users's don't care specifically about style performance, though, but about things like interactivity. We think Servo's style system will improve those things, but don't have numbers for that on hand.
To give a concrete example, it takes Firefox ~1.2 seconds to restyle the single page HTML5 spec with it's current non-parallel style system. Firefox with Stylo can do this in ~300ms. That is close to a full second off of initial page load.
As always, the problem with JITs, especially on the Web, that it's hard to beat the interpreter when you take compilation time into account, and most selectors you see in the wild only apply to a small number of nodes.
So on both of those aspects, the plan here is to go significantly further than any existing major browser.
- Firefox consumes way less ressources than Chrome. I can open 20 tabs it will consume a reasonable amount of memory.
- Firefox crashes way more often than Chrome. I get a crash everyday mostly because of a aggressive Javascript found in pages riddled with ads that abuse tricks in order to force the viewser to see ads ( Adblock can help )
- Firefox is way slower when it comes to Javascript execution than Chrome, no question and it looks like it supports less HTML5 features than the competition.
If Servo can effectively limit Firefox crashes then the investment is worth it. Because that's tne most annoying thing with Firefox. But the amount of memory used by Chrome is just unacceptable, along with spawning 20 processes just because they can ... Chrome is a memory and resource hog.
You could also try to wipe your profile and see how a frugal Firefox without any addons behaves. (Remember to backup your bookmarks to a file before wiping!)
If you have specific pages where you're seeing this, please file bugs on Firefox and add "bzbarsky" to the cc list for the bug!
See https://news.ycombinator.com/item?id=12794971 for examples of such talk, but it's rarely precise enough to file a bug :/