This score item tracks the efficiency of response compression.

IIS can compress static files (static compression) and dynamic responses (dynamic compression ) to reduce transfer times and improve the client experience.

However, some responses may not compress well, resulting in:

  • Wasteful compression that does not yield a meaningful reduction in response size and can cause excessive Cpu overhead.

  • Increased response sizes. Some responses, especially smaller ones, can actually increase in size after compression.

The score is determined by computing the actual avg. compression rate for all responses, and comparing it to the target compression rate (4x by default). The score is further reduced by the volume of response data that is receiving low compression rates.


The diagnostics will automatically identify portions of your application that are producing responses with low compression rates.

You also can review the specific requests that received inefficient compression.

Improving this score

To improve this score, increase the avg. compression efficiency for compressed responses, and reduce the amount of response data that is experiencing poor compression rates.

The primary approach is to stop compressing responses that have poor compression rates. You can do this by:

  • Disabling compression via configuration.

  • Removing the associated mime types from the list of compressible mime types.

  • Increasing the minimum compressible response size, if the low compression rate is due to small responses.

  • Programmatically disabling compression for specific requests.

Proactive guidance

If you are on the Business plan, additional assistance and proactive guidance may be available. Contact support@leansentry.com to learn more.

More resources

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