For IIS 6:

<configuration>
  <system.webServer>
    <staticContent>
      <clientCache cacheControlMode="UseMaxAge" cacheControlMaxAge="7.00:00:00" />
      <remove fileExtension=".js" />
      <mimeMap fileExtension=".js" mimeType="application/javascript" />
    </staticContent>
  </system.webServer>
</configuration>

For IIS 7+:

appcmd.exe set config -section:system.webServer/staticContent 
-clientCache.cacheControlMode:UseMaxAge 
-clientCache.cacheControlMaxAge:"7.00:00:00"

IIS 6 via metabase.xml:

<IIsCompressionScheme Location ="/LM/W3SVC/Filters/Compression/gzip"
   HcCompressionDll="%windir%\system32\inetsrv\gzip.dll"
   HcCreateFlags="1"
   HcDoDynamicCompression="TRUE"
   HcDoStaticCompression="TRUE"
   HcDynamicCompressionLevel="9"
   HcFileExtensions="htm html txt css js"
   HcOnDemandCompLevel="10"
   HcPriority="1"
   HcScriptFileExtensions="asp aspx dll exe"
/>

Remove machine-specific ETags in IIS 7+:

appcmd set config -section:system.webServer/staticContent 
-clientCache.cacheControlCustom:"public"
-clientCache.cacheControlMode:"UseMaxAge"
-clientCache.cacheControlMaxAge:"365.00:00:00"

Key registry tweaks for IIS 6:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\HTTP\Parameters]
"MaxConnections"=dword:0000ffff
"MaxFieldLength"=dword:0000ffff
"MaxRequestBytes"=dword:0000ffff

Complete web.config for IIS 7+ static files:

<configuration>
  <system.webServer>
    <staticContent>
      <clientCache cacheControlMode="UseMaxAge" cacheControlMaxAge="365.00:00:00" />
      <remove fileExtension=".js" />
      <mimeMap fileExtension=".js" mimeType="application/javascript" />
      <remove fileExtension=".css" />
      <mimeMap fileExtension=".css" mimeType="text/css" />
    </staticContent>
    <urlCompression doStaticCompression="true" doDynamicCompression="true" />
    <httpCompression>
      <scheme name="gzip" dll="%Windir%\system32\inetsrv\gzip.dll" />
      <staticTypes>
        <add mimeType="text/*" enabled="true" />
        <add mimeType="application/javascript" enabled="true" />
      </staticTypes>
    </httpCompression>
  </system.webServer>
</configuration>

For high-traffic scenarios, consider these IIS 7 adjustments:

%windir%\system32\inetsrv\appcmd.exe set config /section:serverRuntime 
/frequentHitThreshold:1 
/frequentHitTimePeriod:00:00:30 
/frequentHitSamplePeriod:00:00:30

IIS can be effectively configured as a static file server/CDN alternative. Here's how to implement key optimizations:

For IIS 7+ (recommended approach):

<configuration>
  <system.webServer>
    <httpCompression directory="%SystemDrive%\inetpub\temp\IIS Temporary Compressed Files">
      <scheme name="gzip" dll="%Windir%\system32\inetsrv\gzip.dll" />
      <dynamicTypes>
        <add mimeType="text/*" enabled="true" />
        <add mimeType="application/javascript" enabled="true" />
        <add mimeType="application/x-javascript" enabled="true" />
      </dynamicTypes>
    </httpCompression>
    <urlCompression doStaticCompression="true" doDynamicCompression="true" />
  </system.webServer>
</configuration>

For both IIS 6 and 7:

<configuration>
  <system.webServer>
    <staticContent>
      <clientCache cacheControlMode="UseMaxAge" cacheControlMaxAge="30.00:00:00" />
    </staticContent>
  </system.webServer>
</configuration>

IIS automatically handles these by default, but you can customize:

<configuration>
  <system.webServer>
    <httpProtocol>
      <customHeaders>
        <remove name="ETag" />
        <add name="ETag" value="" />
      </customHeaders>
    </httpProtocol>
  </system.webServer>
</configuration>

Key optimizations for high traffic scenarios:

<configuration>
  <system.webServer>
    <serverRuntime enabled="true" frequentHitThreshold="1" frequentHitTimePeriod="00:00:10" />
    <applicationPool>
      <recycling logEventOnRecycle="Time, Requests">
        <periodicRestart requests="50000" time="00:00:00">
          <schedule>
            <clear />
          </schedule>
        </periodicRestart>
      </recycling>
      <processModel idleTimeout="00:00:00" maxProcesses="1" />
    </applicationPool>
  </system.webServer>
</configuration>

Additional registry settings for IIS 6 (use regedit):

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\InetInfo\Parameters]
"MaxCachedFileSize"=dword:00001000
"ObjectCacheTTL"=dword:0000001e
"MemCacheSize"=dword:00000400

For IIS 7+, use appcmd:

appcmd set config /section:serverRuntime /frequentHitThreshold:1
appcmd set config /section:serverRuntime /frequentHitTimePeriod:00:00:10

Verify your configuration with these tools:

• Fiddler or Chrome DevTools to check response headers
• Webpagetest.org for performance metrics
• IIS Failed Request Tracing for troubleshooting