update readme

README.rst

@@ -78,6 +78,7 @@ Features
 - Porfolio Margin Trading
 - Vanilla Options
 - Proxy support
+- Orjson support for faster JSON parsing
 - Support other domains (.us, .jp, etc)
 
 Upgrading to v1.0.0+
@@ -274,14 +275,20 @@ for more information.
         await client.close_connection()
 
     if __name__ == "__main__":
-
         loop = asyncio.get_event_loop()
         loop.run_until_complete(main())
 
 
 The library is under `MIT license`, that means it's absolutely free for any developer to build commercial and opensource software on top of it, but use it at your own risk with no warranties, as is.
 
 
+Orjson support
+-------------------
+
+Python-binance also supports `orjson` for parsing JSON since it is much faster than the builtin library. This is especially important when using websockets because some exchanges return big messages that need to be parsed and dispatched as quickly as possible.
+
+However, `orjson` is not enabled by default because it is not supported by every python interpreter. If you want to opt-in, you just need to install it (`pip install orjson`) on your local environment. Python-binance will detect the installion and pick it up automatically.
+
 Star history
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