I think values like that are more often used by advertisers, instead of software engineers honestly. It's incredibly tricky to measure the increase of start-up

I think values like that are more often used by advertisers, instead of software engineers honestly. It's incredibly tricky to measure the increase of start-up time as a percentage since it matters so much on hardware, what files you have open, if it's cached, etc. Using a single percentage would probably be more misleading than just saying "significantly improved".