Since PEP 560 was approved,
The following syntax has become available. 

from queue import Queue
v = Queue[int]

It's a very shiny feature.
Given the direction of programming language, it's probably a very useful feature that users will use very often in the near future.

When I looked at Object/geneticiasobject.c, the current implementation is a very good condition for using the vectorcall proposed by PEP590 .

The benchmarks are as follows.
So I suggest using vectorcall in GenericAlias.

if the suggestion is accepted, I 'd like to summit the patch :)


+--------------------+----------------------+-----------------------------+
| Benchmark          | master-generic-alias | proposed-generic-alias      |
+====================+======================+=============================+
| bench GenericAlias | 143 ns               | 111 ns: 1.29x faster (-22%) |
+--------------------+----------------------+-----------------------------+