+1 for Blacksmith. You need to have a Github org to use it as it won't work on personal accounts, but it feels like a magic want that just makes runners 2x as fast.

I have it for all my stuff (dozens of repos and hundreds of PRs/builds per week) and it's only once in the last year that I've exceeded the free resource levels. I don't know if it's just extra capacity or they're burning VC dollars in the hopes of inspiring posts like this, but either way I feel like I'm taking advantage of them at this point.