Skip navigation

JSI Tip 1011. Improve Performance Monitor performance.

If you use extensible counters, you can improve Performance Monitor performance, if Service Pack 3 or later is installed.

By default, Perfmon inspects the buffers returned by extensible counters. This can cause NT to fail and certainly causes Perfmon to use more resources. The ExtCounterTestLevel registry value has a new entry, 4, which was added in SP3. Navigate to:


and Add Value name ExtCounterTestLevel as a type REG_DWORD.

NOTE: - If the Perfmon key does not exist, run Perfmon to create it.

The data values for ExtCounterTestLevel are:

1    High. The Performance Library tests extensible counter pointers and buffers thoroughly.*

2    Medium. The Performance Library checks pointers and buffer length


3    Low. The Performance Library does not test pointers or buffers.


4    None. The Performance Library does not test pointers or buffers.

Shutdown and restart for this change to take effect.

* The extensible counter is sent a copy of the buffer, so the actual buffer can not be damaged.

NOTE: - The default prior to SP3 was 1. SP3+ is supposed to set the default to 4, but you should set it to be sure.

Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.