Windows 7 Slow Network Access or Accessing Network Shared Drive Data

Windows 7 Slow Network Access or Accessing Network Shared Drive Data

Issue

Windows 7 PC attempts to accesss file shares , browsing performance of mapped network shares becomes very slow.  It feels simlar to accessing the file server over a VPN connection with poor bandwidth and high latency, however in this scenario we are accessing the file server over LAN.
This issue is not driver related, I ensured to test workstations of different driver architecture including Intel and Broadcom network drivers.

Workaround

After researching into this issue we came identified two Windows components contributing to the performance issues.

• TCP Auto-Tuning
• Remote Differential Compression

Do not disable these components unless you understand what they are and their purpose.

TCP Auto-Tuning

A new TCP stack was implemented that aims to take full advantage of hardware advances such as gigabit networking. Among the new feature in the new TCP stack is Receive Window Auto-Tuning Level for TCP connections.

TCP AutoTuning enables TCP indow scaling by default and automatically tunes the TCP receive window size for each individual connection based on the bandwidth delay product (BDP) and the rate at which the application reads data from the connection, and no longer need to manually change TcpWindowSize registry key value which applies to all connection.

The default auto-tuning level is “normal”, and the possible settings for the above command are:

disabled: uses a fixed value for the tcp receive window. Limits it to 64KB (limited at 65535).
highlyrestricted: allows the receive window to grow beyond its default value, very conservatively
restricted: somewhat restricted growth of the tcp receive window beyond its default value
normal: default value, allows the receive window to grow to accommodate most conditions
experimental: allows the receive window to grow to accommodate extreme scenarios (not recommended, it can degrade performance in common scenarios, only intended for research purposes. It enables RWIN values of over 16 MB)

In my environment changing this from the default value of normal to restricted resolved my performance issues.

netsh int tcp set global autotuninglevel=restricted

Remote Differential Compression

Remote Differential Compression (RDC) is a client–server synchronization algorithm that allows the contents of two files to be synchronized by communicating only the differences between them. It was introduced with Windows Server 2003 R2 and is included with later Windows client and server operating systems.  As of Vista onwards Remote Differential Compression is enabled by default.

You can disable RDC through Windows Features in control panel: