You’re mixing up things.
Performance w/ your 4090 and temps has nothing to do with any (network) lag you may have experienced.
Lag = network lag= high/spiky latency and/or packet loss. Rubber banding is an issue between the server, the internet and getting to your PC and the reverse. It could be any of the 3 at fault, typically it’s the server and its host, but there have been times where bad stuff hits the 'net at large.
You could have a RTX 5090 with a Ryzen 9 8900x and still have network lag mucking things up.
P.S. These days, too many people erroneously call choppy/low framerates “lag” too, which is confusing, sometimes the “network” and “framerate” qualifiers are used.
it was rather meant as a distinction between the gpu not being the culprit due to bad performance / fps and the issue being only present in one scenario despite almost identical factors.
so the intention was to point in the direction of sever issues/something outside my system,
sorry if i wrote a bit garbled
while writing from work usually works fine, sometimes you get called from the screen and finish half an hour later