The Windows Internet Information Services (IIS) Manager caches compressed static content in the path that is specified by the directory attribute. This caching improves compression performance by eliminating the need to recompress content. After IIS has compressed a file, subsequent requests receive the compressed copy of the file from the cache folder.
Image files such as *.jpg and *.png files are also static files, but typically they
do not benefit from HTTP compression because these image files are already compressed.
The steps below provide basic information for enabling and disabling static compression. See the documentation for your specific IIS Manager for details.
Enable static compression for a site or application
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Open the Internet Information Services (IIS) Manager.
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In the Connections pane, go to the connection, site, application, or folder to enable compression.
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In the Home pane, double-click Compression, and then check Enable static content compression.
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Click Apply in the Actions pane.
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Open the IIS Configuration Editor and perform the following in the specified sections:
Section system.webServer/serverRuntime:
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Click the Unlock section.
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Change frequentHitThreshold from 2 to 1.
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Change frequentHitTimePeriod from 00:00:10 to 10000.00:00:00.
Section system.webServer/httpCompression:
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Increase the maxDiskSpaceUsage as the default value of 100 MB is too small. We recommend 10 GB or more, if possible. If you continue to use the default (100 MB), the server must constantly recompress files.
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Change staticCompressionIgnoreHitFrequency from False to True.
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Edit the staticTypes, and then add application/octet-stream and application/wasm.
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Change sendCacheHeaders from False to True.
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The same configuration can be set directly in the root web.config:
When Static compression is enabled, you can see Content-Encoding: gzip in the Response Headers whenever the application requests data on the static compression-enabled server.
The transferred data is also reduced for static compression.
