These tweak are very old and are designed for Win 2000 and Windows XP
These was the times of 56K Modems and you could use tools to tweak.
Some people still use these software and believe they improve internet performance, I think nowadays its all a placebo effect.
Modem Tweak Tools:
Tweak Master
CableNut
TCP Optimizer
There is loads of others out there.
CableNut Settings: For TCP/IP and AFD registry parameters
DefaultReceiveWindow = 8192
DefaultSendWindow = 4096
DisableAddressSharing = 1
InitialLargeBufferCount = 20
InitialMediumBufferCount = 48
InitialSmallBufferCount = 64
LargeBufferSize = 40960
MaxFastTransmit = 6400
MediumBufferSize = 15040
PriorityBoost = 0
SmallBufferSize = 1280
TransmitWorker = 32
FastSendDatagramThreshold = 1024
EnableFastRouteLookup = 1
EnablePMTUDiscovery = 1
IgnorePushBitOnReceives = 0
GlobalMaxTcpWindowSize = 8760
MaxFreeTcbs = 4000
MaxHashTableSize = 8192
MaxNormLookupMemory = 1500000
SackOpts = 1
SynAttackProtect = 1
Tcp1323Opts = 0
TcpLogLevel = 1
MaxDupAcks = 3
TcpMaxHalfOpen = 100
TcpMaxHalfOpenRetried = 80
TcpRecvSegmentSize = 1460
TcpSendSegmentSize = 1460
TcpTimedWaitDelay = 30
TcpUseRFC1122UrgentPointer = 0
TcpWindowSize = 8760
MaxConnectionsPer1_0Server = 8
MaxConnectionsPerServer = 4
DefaultTTL = 128
DisableUserTOSSetting = 0
TcpMaxDataRetransmissions = 6
DefaultTOSValue = 90
These tweaks vary for user to user.
More
Here