If you want to connect to the built-in macOS remote desktop server, don't use a standard VNC client, use a real ARD client like Remote Desktop Manager. While the server accepts standard VNC, you will only get zlib the codec, which has very poor performance. With ARD, you get a special codec inspired by progressive JPEG, along with server-side downscaling and chroma subsampling, etc. It's actually closer to RDP RemoteFX in terms of performance: https://devolutions.net/integration-center/apple-remote-desk...