Summary

I found this to be slow when type checking:

from collections import OrderedDict

OrderedDict(OrderedDict(OrderedDict(OrderedDict(OrderedDict(OrderedDict(("one", 1)))))))

Playground

This takes about 11 seconds on my machine.

The example was found using a fuzzer.
While this example is not a real program someone would write, I'm submitting it in case the root cause can slow down ty in other situations that are useful. Feel free to close if it's unrelated.

Version

0.15.7+22 (dd6d84305 2026-03-21)