You should probably enable gzip in your web.config
<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="message/*" enabled="true"/>
<add mimeType="application/javascript" enabled="true"/>
<add mimeType="*/*" enabled="false"/>
</dynamicTypes>
<staticTypes>
<add mimeType="text/*" enabled="true"/>
<add mimeType="message/*" enabled="true"/>
<add mimeType="application/javascript" enabled="true"/>
<add mimeType="*/*" enabled="false"/>
</staticTypes>
</httpCompression>
<urlCompression doStaticCompression="true" doDynamicCompression="true"/>
</system.webServer>
There are a few more tricks here
Setting the gzip compression in asp.net