Updates to performance testing

[Eli Perelman]

Hello Gaia,

As part of our task to improve the state of performance testing, I will be making changes to the scripts we use to generate performance markers in the apps, and making changes to the apps themselves eventually. During this transition, all the apps will temporarily include 2 performance scripts while I phase out the old one. Adding an additional script I expect will regress launch time by around 10ms or less, but once the transition is complete we will gain it back by removing the original script. If you have any concerns please let me know.

Thanks,

Eli Perelman