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TCP Optimizer Revision History

2015-04-04 (updated: 2021-01-08) by

The latest build of the SG TCP Optimizer can be downloaded from our downloads section. Documentation for the latest version of the program is available here: SG TCP Optimizer 4 Documentation. Below is a list of updates, changes, and bug fixes the program.

TCP Optimizer v. 4.1.1 (2021.01.08)

  • Changed the recommended "optimal" congestion control algorithm from CTCP to CUBIC for newer Windows 10 and Server 2019 builds. CUBIC works slightly better for pure throughput, CTCP may work slightly better for VoIP and gaming in combination with ECN and lossy connections.

TCP Optimizer v. 4.1.0 (2019.02.22)

  • Changed the Windows 8/8.1 command for InitialRTO to netsh (PowerShell cmdlets don't have sufficient permissions to change the value for the Internet template)
  • Updated Windows minor versions detection algorithm

TCP Optimizer v. 4.0.9 (2018.07.23)

  • Updated RSS (Receive-Side Scaling) and RSC (Receive Segment Coalescing) settings to be read using PowerShell on startup, should now also work better for international Windows variants.
  • Changed RSC optimal setting to disabled (issues with some Wi-Fi networks, also reduced delay when disabled in general)
  • Updated heading to properly read "Windows 10 Pro" instead of "Enterprise"

TCP Optimizer v. 4.0.8 (2018.07.11)

  • Fixed typo in applying LargeSendOffload parameter.

TCP Optimizer v. 4.0.7 (2018.04.20)

  • Optimizer is now aware of, reads and displays the current TCP/IP settings "template".
  • Updated Congestion Control Provider command, added "CUBIC" and "NewReno" algorithms introduced with Windows 10 Creators Update.
  • Changed RSS (Receive-Side Scaling) and RSC (Receive Segment Coalescing) settings to be applied globally.
  • Fixed Chimney Offload command (made change global) and program now reads setting on startup.
  • Changed default to modify all network adapters.
  • Removed obsolete DCA (Direct Cache Access) setting.
  • Program now reads most settings on startup.

TCP Optimizer v. 4.0.6 (2016.09.07)

  • Changed recommended optimal TCP Auto Tuning level from "experimental" to "normal" for fast connections over 100 Mbps to avoid some LAN shares issues
  • Updated recommended optimal TCP Auto Tuning level from "restricted" to "disabled" for connection speeds under 512 Kbps.

TCP Optimizer v. 4.0.5 (2016.05.03)

  • Minor update that only affects custom advanced settings. Fixed a bug where a couple of advanced settings would not be deleted in custom mode if dialog is left empty by the user.

TCP Optimizer v. 4.0.4 (2016.03.15)

  • Changed "optimal" recommendation for "TCP Chimney Offload" to "disabled" due to the setting causing issues with some servers and now considered deprecated by Microsoft. See: Obsolete RFCs and Overview of TCP Timers

TCP Optimizer v. 4.03 (2015.10.27)

  • Changed "current" state under Windows 8/10 to display empty lines for dialogs that are not read at program start to avoid confusion

TCP Optimizer v. 4.02 (2015.10.12)

  • Fixed a minor bug to correctly read current "InitialRTO" and "MinRTO" advanced settings under Windows 8.1/10

TCP Optimizer v. 4.01 (2015.09.25)

  • Updated OS detection algorithm to make the program more robust. Unknown OS versions will assume the latest supported (currently Windows 10)

TCP Optimizer v. 4.00 Beta (2015.04.20):

  • Updated OS detection for Windows 8, 8.1, 10, 2012 Server, 2012 Server R2, Windows 10
  • Updated all settings that work with Windows 8,8.1,2012 Server, 2012 Server R2, Windows 10
  • Fixed MaxConnectionsPerServer (switched HTTP 1.0 and 1.1 setting) and updated optimal from 8 to 10 connections
  • Changed NetDMA "optimal" state for Windows 7, disabled unsupported setting for Windows 8 and later
  • Added PowerShell cmdlets handling for Windows 8/8.1/2012/10 support
  • Added all new relevant tweaking options under Windows 8 and newer.
  • Added new TCP Offload tweakable parameters
  • Added the "SystemResponsiveness" gaming tweak
  • Updated reset of TCP/IP and Winsock for Windows 8/2012
  • Reordered the settings for more consistent appearance across newer OSes (Windows Vista and newer)
  • Updated Nagle's Algorithm Registry hive to include a second location
  • Reduced optimal TCP Max Data Retransmissions to 5
  • Added "Create Log" checkmark to "Apply Settings" dialog that logs all executed commands by the program
  • Updated default URLs in "Preferences" menu to ones that respond to ICMP pings.
  • Updated unsupported settings for Windows 8 and newer: SynAttackProtect,TCPMaxDataRetransmissions, replaced with relevant PowerShell cmdlets
  • Removed for Windows 8 and newer: NetDMA, DNS Error Caching
  • Some bug fixes and minor internal improvements
  • 2015.04.28 - updated backup/restore menus
  • 2015.04.28 - added MTU IPv6 support for Windows 7 and newer
  • 2015.04.28 - fixed MTU setting for Windows 8/8.1/10/2012
  • 2015.04.29 - updated Nagle's algorithm tweak to include more options
  • 2015.04.29 - fixed TCPNoDelay and TcpDelAckTicks reading of "current" values.
  • 2015.04.30 - changed to multithreaded mode for reading of PowerShell cmdlets with Windows 8 and newer.
  • 2015.04.30 - updated initial loading dialog to be more informative and show executed commands under Windows 8 and newer (necessary because of PowerShell cmdlets delay).
  • 2015.04.30 - changed per adapter Large Send Offload (LSO) current reading for IPv4.
  • 2015.05.19 - updated Windows default SystemResponsiveness for Windows 2008/2012 Server from 20 to 100.
  • 2015.05.19 - added "Do not use NLA" QoS option to allow setting DSCP values without the need to join a domain, and for multiple NICs.

TCP Optimizer v. 3.0.8 (2011.09.17):

  • Added NetworkThrottlingIndex gaming tweak to the Advanced tab
  • Changed "MaxUserPort" optimal value from 65535 to 65534.
  • minor internal improvements

TCP Optimizer v. 3.0.7 (2011.03.22):

  • Improved international Windows support (MTU should be correctly recognized and modified for most countries/network adapters)
  • Increased MTU limit to 9000 to accomodate some Gigabit connections
  • Changed ECN Capability optimal recommendation in General tab based on user feedback and issues with some US ISPs
  • Fixed a minor issue with TcpAckFrequency and TcpDelAckTicks not applied only in "custom" mode in some cases where the Network adapter is not recognized

TCP Optimizer v. 3.0.6 (2010.10.06):

  • fixed a possible program crash condition under Windows 2008 Server R2
  • added traceroute capability to the MTU/Latency tab
  • improved netsh current settings reading under Swedish versions of Windows

TCP Optimizer v. 3.0.5 (2010.09.16):

  • fixed a 3.x Windows XP bug - only when choosing to "modify all network adapters", two advanced settings (TcpAckFrequency and TCPDelAckTicks) were set incorrectly.
  • Improved International Windows support (reading current netsh settings).
  • minor internal improvements

TCP Optimizer v. 3.0.4 (2010.09.06):

  • Improved International Windows support - netsh current settings in the General tab should now be read correctly for many languages
  • minor internal improvements

TCP Optimizer v. 3.0.3 (2010.07.29):

  • changed 64-bit OS handling to avoid 32-bit access issues causing some netsh settings not to remain persistent after reboot
  • changed Direct Cache Access (DCA) and NetDMA (TCPA) handling in Windows 7
  • minor internal improvements

TCP Optimizer v. 3.0.2 (2010.07.12):

  • added "Dynamic port allocation" (MaxUserPort, TcpTimedWaitDelay) for Windows XP/2003
  • added "Checksum Offloading" (DisableTaskOffload) setting for Windows 7/Vista/2008/XP/2k3
  • added a "Copy current settings" option to the File menu for easy sharing of current settings (forum posting, etc.)
  • fixed incorrect error message under Chinese versions of Windows 7 x86.

TCP Optimizer v. 3.0.1 (2010.07.09):

  • fixed reading current settings correctly under XP
  • temporarily disabled incorrect error message under Windows 7 x64 after applying changes
  • Enabled Gaming tweak (disable Nagle's algorithm) in Windows XP mode
  • minor cosmetic/message updates

TCP Optimizer v. 3.0 (RC1, 2010.07.07):

  • complete rewrite of the General tab to support Windows 7, Vista, and Server 2008 - different look and settings under Windows 7/Vista vs. XP/2k
  • increased connection speed slider to 100+ Mbps
  • added an easier method to revert to the Windows default settings per OS version
  • added options to reset TCP/IP and Winsock
  • Combined Latency and BDP tabs into one, updated Largest MTU algorithm and sites to ping
  • various minor improvements

Known issues: when applying some custom settings, you may see an error: "Set global command failed on IPv4 The parameter is incorrect". The settings are being applied (can be verified by restarting the Optimizer and checking "current" settings), just the error is incorrectly displayed.

Changes in TCP Optimizer v. 2.0.3 :

  • Under Optimal or Custom mode, when PPPoE is checked, and the MTU is not modified manually, the displayed 1492 MTU is now correctly applied to the Registry.
  • If MTU is set to a value outside the valid range, and the user changes current/optimal/custom mode, the value is now properly reset to 1500.
  • The Latency tab will account for, and discard incorrect negative RTT values sometimes returned by servers. Such values will no longer count towards the min/max/avg calculations.

Changes in TCP Optimizer v. 2.0.2 :

  • Added all virtual Network Adapters to the list of NICs.
  • Changed the NegativeCacheTime Windows 2000 entry to MaxNegativeCacheTtl for Windows XP and 2003 Server (DNS Caching).
  • Added Scaled RWIN and Tcp1323 Options for Windows 95 machines as requested (a MS update to Windows 95 is also necessary for this to work)
  • Removed the ToS/QoS control box frame, LAN Browsing speedup, and LAN Request Buffer size from Windows 9x Advanced settings.
  • Changed custom mode to display the current values by default, rather than optimal ones.
  • Fixed the Windows 9x Advanced settings optimal/custom modes to display the correct Host Resolution Priorityy
  • Fixed the RWIN calculation to take into account custom latency selection after program restart.
  • Updated the Windows 9x RWIN calculation to match the Windows XP/2k/2k3 algorithm

Changes in TCP Optimizer v. 2.0.1 :

  • Fixed a bug where DefaultTTL was set to "0" instead of "64" under "Optimal settings" in Windows 9x.
  • Fixed the "LAN Browsing speedup" to correctly show "Optimized" under current settings when applicable.
  • Changed "Connection speed" slider bar to accommodate faster broadband connections as per users' requests.
  • Changed "Connection speed" slider bar to retain last user-selected speed setting after program restart.

Changes in TCP Optimizer v. 2.0.0 (from version 1.0):

  • Added a new tab with a BDP (Bandwidth*Delay Product) calculator
  • Registry tab is now an editor, users can edit/add/delete keys in related hives.
  • Changed the connection speed to a more flexible slider bar.
  • Changed the RWIN calculation to reflect various speeds, optimal RWIN is now recalculated on the fly.
  • Added Afd check for the RWIN value, to avoid confusion with XP SP2.
  • Enabled custom MTU values under "Optimal settings."
  • Added check for AOL and PPPoE "Protocol MTU" for clients that have, or have had AOL installed.
  • Added QoS / ToS editing to the "Advanced settings" tab.
  • Added DNS error caching fix
  • Added Host Resolution Priority tweak
  • Added LAN "Request Buffer Size" tweak
  • Automatic backup of related registry keys before changing any values.
  • Expanded the import/export/backup capabilities.
  • Added "Preferences" to the program, users can now choose URLs for the Latency tab, as well as "maximum anticipated delay" for RWIN calculations.
  • Added a preview of changes, after clicking "Apply changes" and before they're actually applied.
  • Added documentation.

See Also:

TCP Optimizer Download
TCP Optimizer 4 Documentation
TCP Optimizer FAQ


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