Possibly Shopify's monolith.

Or alternatively someone is doing something very silly.

Nah, they replaced GitHub with some in-house videcoded stuff a few months ago, and from what I hear from the grapevine it's not going well.

But there's a number of other big private repos with a high rate of merge on GitHub, and indeed it's currently a bit painful, e.g. the subroutine that check whether a PR can be merged tend to take ages. So my read is that they want to better support these big customers out of concern that they might leave too.

This is just cringeworthy, even for Tobi.

The biggest very active repo I know of is nixpkgs, and I heard it was a stress test for GitHub already.

Possibly this dude's repos? https://github.com/xesf

Every day, he sends hundreds of commits to his (most likely vibecoded) repositories of retro games recompilation.

[delayed]

It's probably a horror story if we ever find out.

Given its prominence in some of these other discussions from GitHub of a repo always on their performance radar now my gut instinct is that it could be the Windows monorepo.

Windows? We know it's on Git, and Microsoft owning GitHub means it would make sense for it to be on GitHub.

Alternatively, something from IBM with 60 years of commit history.