Enabling static file compression on IIS

web.config

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <system.webServer>
        <validation validateIntegratedModeConfiguration="false" />
        <urlCompression doStaticCompression="true" doDynamicCompression="true" dynamicCompressionBeforeCache="false" />
        <!--minification requires dynamicCompressionBeforeCache off, order of operations error?-->
        <httpCompression noCompressionForHttp10="false" noCompressionForProxies="false" staticCompressionIgnoreHitFrequency="true" />
        <!--If your IIS server has this unlocked, uncomment
        <serverRuntime frequentHitThreshold="1" frequentHitTimePeriod="00:00:10" enabled="true" />
        -->
        <staticContent>
            <clientCache cacheControlMode="UseMaxAge" cacheControlMaxAge="49.00:00:00" />
            <remove fileExtension=".woff2" />
            <mimeMap fileExtension=".woff2" mimeType="application/font-woff2" />
        </staticContent>
        <caching enabled="true">
            <profiles>
                <add extension=".ico" policy="CacheUntilChange" kernelCachePolicy="DontCache" duration="49.00:00:00" location="Downstream" varyByQueryString="*" varyByHeaders="Accept-Encoding" />
                <add extension=".png" policy="CacheUntilChange" kernelCachePolicy="DontCache" duration="49.00:00:00" location="Downstream" varyByQueryString="*" varyByHeaders="Accept-Encoding" />
                <add extension=".jpg" policy="CacheUntilChange" kernelCachePolicy="DontCache" duration="49.00:00:00" location="Downstream" varyByQueryString="*" varyByHeaders="Accept-Encoding" />
                <add extension=".gif" policy="CacheUntilChange" kernelCachePolicy="DontCache" duration="49.00:00:00" location="Downstream" varyByQueryString="*" varyByHeaders="Accept-Encoding" />
                <add extension=".eot" policy="CacheUntilChange" kernelCachePolicy="DontCache" duration="49.00:00:00" location="Downstream" varyByQueryString="*" varyByHeaders="Accept-Encoding" />
                <add extension=".ttf" policy="CacheUntilChange" kernelCachePolicy="DontCache" duration="49.00:00:00" location="Downstream" varyByQueryString="*" varyByHeaders="Accept-Encoding" />
                <add extension=".woff" policy="CacheUntilChange" kernelCachePolicy="DontCache" duration="49.00:00:00" location="Downstream" varyByQueryString="*" varyByHeaders="Accept-Encoding" />
                <add extension=".woff2" policy="CacheUntilChange" kernelCachePolicy="DontCache" duration="49.00:00:00" location="Downstream" varyByQueryString="*" varyByHeaders="Accept-Encoding" />
                <add extension=".htc" policy="CacheUntilChange" kernelCachePolicy="DontCache" duration="49.00:00:00" location="Downstream" varyByQueryString="*" varyByHeaders="Accept-Encoding" />
                <add extension=".svg" policy="CacheUntilChange" kernelCachePolicy="DontCache" duration="49.00:00:00" location="Downstream" varyByQueryString="*" varyByHeaders="Accept-Encoding" />
                <add extension=".css" policy="CacheUntilChange" kernelCachePolicy="DontCache" duration="49.00:00:00" location="Downstream" varyByQueryString="*" varyByHeaders="Accept-Encoding" />
                <add extension=".js" policy="CacheUntilChange" kernelCachePolicy="DontCache" duration="49.00:00:00" location="Downstream" varyByQueryString="*" varyByHeaders="Cookies, Accept-Encoding" />
                <add extension=".xml" policy="CacheUntilChange" kernelCachePolicy="DontCache" duration="49.00:00:00" location="Downstream" varyByQueryString="*" varyByHeaders="Accept-Encoding" />
                <add extension=".txt" policy="CacheUntilChange" kernelCachePolicy="DontCache" duration="49.00:00:00" location="Downstream" varyByQueryString="*" varyByHeaders="Accept-Encoding" />
            </profiles>
        </caching>
        <modules runAllManagedModulesForAllRequests="true" />
        <httpProtocol>
            <customHeaders>
                <clear />
                <remove name="Access-Control-Allow-Origin" />
                <add name="Access-Control-Allow-Origin" value="*" />
                <remove name="Access-Control-Allow-Headers" />
                <add name="Access-Control-Allow-Headers" value="Content-Type" />
            </customHeaders>
        </httpProtocol>
    </system.webServer>
</configuration>

If you're in a bare IIS site, you might have to be explicit about the modules you want to run, also make sure your vary-bys match your usage... these are for no-cookie, etc.

Lastly you may need to unlock the serverRuntime element of your machine configuration, I do this with these commands in a cmd file

@echo off
%SystemRoot%\System32\inetsrv\appcmd.exe unlock config /section:system.webServer/serverRuntime
%SystemRoot%\System32\inetsrv\appcmd set config /section:httpCompression /+staticTypes.[mimeType='image/*',enabled='true'] /commit:apphost
%SystemRoot%\System32\inetsrv\appcmd set config /section:httpCompression /+dynamicTypes.[mimeType='image/*',enabled='true'] /commit:apphost
%SystemRoot%\System32\inetsrv\appcmd set config /section:httpCompression /+staticTypes.[mimeType='application/octet-stream',enabled='true'] /commit:apphost
%SystemRoot%\System32\inetsrv\appcmd set config /section:httpCompression /+dynamicTypes.[mimeType='application/octet-stream',enabled='true'] /commit:apphost