jqGrid for ASP.NET uses JSON (JavaScript Object Notation) to send row data from server to client on AJAX request. JSON is already regarded as the fastest and most optimized communication protocol for the web. jqGrid takes that even further, by only sending raw cell data - no HTML, no CSS styles, no metadata, etc. This means that you can get very fast load times for pages of hundreds and even thousands of rows at once.

One additional tip you can use to speed this up is to use GZip compression for the JSON response type in IIS. Browsers support GZip compression and automatically decompress the response prior to using it - this can reduce the request/response size several times.

More info on how this can be achieved can be found here:
http://forums.iis.net/p/1155809/1895877.aspx