DeflatePerMessage VS memory consumption

[M1ha-Shvn]

Hi.
I'm devloping a server serving websockets connections using FastAPI.
I've noticed, that creating several thousands of simultinious websocket connections leads to high memory usage (4 Gb per 5-8k websocket connections in my case). I've started debugging it with tracemalloc and found out that the largest amount of this memory is consumed by websockets deflate extension in this line.
After that I've digged into websockets deflate mechanics and found out that it can be tuned wisely in order to achive lower memory consumption using custom ServerPerMessageDeflateFactory. I've tried searching for it in FastApi => Starlette => Uvicorn code and it lead me here.
What is the source of memory leak:

1. Uvicorn creates separate PerMessageDeflate instance for each websocket connection (using ServerPerMessageDeflateFactory). From my point of view, it is a disadvantageous behaviour: it would be much better if it is created not for each websocket connection, but for each combination of connection parameters (like Singleton pattern, but created for each combination of parameters. Something like lru_cache).
2. The only setting uvicorn gives to tune deflate is just disabling it with --ws-per-message-deflate. It is not flexible for different cases.

[M1ha-Shvn]

Upd: disabling deflate solves leaking memory. So my hypothesis looks correct. Should I open an issue?

[Kludex]

Created #1862 from this discussion.