delete.term can be slow - maybe after it says Done?

[ceedubs]

Describe and demonstrate the bug

Here I'm deleting an unused term on a branch that is close to the main branch of nimbus.

@cloud/nimbus/cleanup-2> delete.term services.fetchBlobFromFilesystem
updateRoot: 76.6 ms (cpu), 62.9 ms (system)
 
  Done.

InputPattern: 24.6 s (cpu), 11.9 s (system)

As you can see from the output the InputPattern timing is pretty slow; it feels like a long time to wait.

The output also shows that updateRoot is relatively fast. So there's a question of where the slowness is coming in. Perhaps in a dependency check to make sure that nothing is calling it? But dependents doesn't seem to be this slow.

Environment (please complete the following information):

• ucm built from commit 335512e
• OS/Architecture: NixOS 23.11 (Tapir); x86; 32 GB RAM; 16 cores
• Browser, if applicable: N/A

[ceedubs]

Notably delete.namespace is significantly faster. Though it is also known to have a bug in which it can lead to unnamed dependencies, so maybe it's taking a shortcut that it shouldn't be.