welcome to the forum Drakrum
speed is great, so your settings is fine
There is a formula for calculating teoretical maximal speed if you know latency, MSS and RWIN
its however very hard, to find a accurate latency cos it change during a download / upload
You could try increasing/ decrease GlobalMaxTcpWindowSize and TcpWindowSize ( set them to the same value )
If the value is smaller then 65536 then set Tcp123Opts to 0
s suggestion is to use maximal unscaled GlobalMaxTcpWindowSize and TcpWindowSize thats multiple with your MSS, for you its 64240
VanBuren