Update README to include performance note

README.md

@@ -65,9 +65,24 @@ want to process a stream of bytes without regard to those boundaries, try
 [`ws_stream_tungstenite`](https://crates.io/crates/ws_stream_tungstenite),
 which builds upon this crate.
 
+## Is it performant?
+
+In essence, `async-tungstenite` is a wrapper for `tungstenite`, so the performance is capped by the performance of `tungstenite`. `tungstenite`
+has a decent performance (it has been used in production for real-time communication software, video conferencing, etc), but it's definitely
+not the fastest WebSocket library in the world at the moment of writing this note.
+
+If performance is of a paramount importance for you (especially if you send **large messages**), then you might want to check other libraries
+that have been designed to be performant or you could file a PR against `tungstenite` to improve the performance!
+
+We are aware of changes that both `tungstenite` and `async-tungstenite` need in order to fill the gap of ~30% performance difference between `tungstenite`
+and more performant libraries like `fastbwebsockets`, but we have not worked on that yet as it was not required for the use case that original authors designed
+the library for. In the course of past years we have merged several performance improvements submitted by the awesome community of Rust users who helped to improve
+the library! For a quick summary of the pending performance problems/improvements, see [the comment](https://github.com/snapview/tungstenite-rs/issues/352#issuecomment-1537488614).
+
 ## tokio-tungstenite
 
 Originally this crate was created as a fork of
 [tokio-tungstenite](https://github.com/snapview/tokio-tungstenite) and ported
 to the traits of the [`futures`](https://crates.io/crates/futures) crate.
 Integration into async-std, tokio and gio was added on top of that.
+