Adjust TCP Delayed ACK Timer in Windows Regedit

Adjusting the TCP delayed acknowledgment (ACK) timer in the Windows Registry allows you to decrease network latency by forcing the operating system to respond immediately to incoming network packets rather than waiting for the default delay period. This article provides a direct, step-by-step guide to modifying the TcpAckFrequency and TcpDelAckTicks registry parameters across your network interfaces using the Windows Registry Editor (regedit).

Step 1: Open the Registry Editor

  1. Press Win + R to open the Run dialog box.
  2. Type regedit and press Enter (or click OK).
  3. If prompted by User Account Control (UAC), click Yes to grant administrative privileges.

Step 2: Navigate to the Network Interfaces Key

In the Registry Editor address bar, paste the following path and press Enter:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces

Under the Interfaces key, you will see several subkeys with long alphanumeric strings (GUIDs). Each GUID represents a network adapter on your system.

To find your active network adapter: 1. Click through each GUID folder. 2. Look for the IPAddress or DhcpIPAddress entry in the right pane. 3. Identify the GUID folder that displays your active local network IP address (e.g., 192.168.1.X).

Step 3: Configure TcpAckFrequency

TcpAckFrequency specifies the number of TCP ACKs that are outstanding before the delayed ACK timer is ignored.

  1. Right-click inside the empty space of the active adapter’s GUID folder.
  2. Select New > DWORD (32-bit) Value.
  3. Name the new value TcpAckFrequency and press Enter.
  4. Double-click TcpAckFrequency.
  5. Set the Base to Hexadecimal (or Decimal).
  6. Set the Value data to 1 (this disables the delay and sends an ACK for every packet).
  7. Click OK.

Step 4: Configure TcpDelAckTicks

TcpDelAckTicks directly controls the delayed ACK timer interval (measured in 100-millisecond ticks).

  1. In the same active adapter folder, right-click an empty space.
  2. Select New > DWORD (32-bit) Value.
  3. Name the new value TcpDelAckTicks and press Enter.
  4. Double-click TcpDelAckTicks.
  5. Set the Base to Hexadecimal (or Decimal).
  6. Set the Value data to 0 to disable delayed ACKs entirely, or enter a value between 1 and 6 (where each tick equals 100ms; default Windows behavior is 2, representing 200ms).
  7. Click OK.

Step 5: Restart the System

Registry modifications to TCP/IP parameters do not take effect immediately. Restart your computer or disable and re-enable your network adapter to apply the new TCP acknowledgment settings.