[plorkyeran]

Google has not shared any actual evidence that there's a performance gain to be had. Non-google benchmarks of uBO show it not being a performance problem in the first place, so there simply isn't much room to be faster than it.

[SquareWheel]

uBO is not the only adblocker around. It's likely not even the most popular. These changes will apply to all of them, bringing the baseline of performance up.