[Matthias247]

QUIC will help with some things, and make others worse. With QUIC you don't need a file descriptor per connection anymore. A single file descriptor for one UDP socket will be sufficient to handle an arbitrary amount of connections (although you might want more to actually exploit concurrency). That fact will help limiting resources that the kernel uses. However the state that needs to be tracked per established connection is likely way larger than for TCP, due to being a more complex and featureful protocol. E.g. QUIC needs state for tracking sub-streams on a connection, while TCP does not. And of course there's all the mandatory crypto state. I am fairly familiar with QUIC implementations, and made a multitude of changes in various libraries (e.g. Quinn and s2n-quic). I wouldn't be surprised if the baseline memory usage of a QUIC connection in most libraries is > 10x of what the Linux TCP stack requires for tracking a connection