list_subscript/_PyList_Subscript is the general subscript function for lists. I think we want to use a more specialized function that only works for slices. i.e this code: https://github.com/python/cpython/blob/main/Objects/listobject.c#L3614-L3618

The stats diff show a 50x increase in "subscr tuple slice" as a cause of specialization failure. Any idea why that might be? I can't see any reason for it.