Is 30 calls / second a lot for one IIS server?

We have a RIA application that 300 clients concurrently use in an intranet environment. Together they make 30 calls / second to IIS (asp.net) (actually it's 60 but calls are loadbalanced over two IIS servers). Half of the calls is getting an asset (Caching Profile is used so most of the time cache is hit), the other half is saving data to a sql server.

Retrieving an asset is done with a aspx page. Saving the data happens via WebORB, asp.net and Sql Server. So some processing is needed by WebORB (amf decoding, GZIP, ...). We also use Spring.NET, and some of the container objects have a request scope (not a lot).

IIS servers --> Virtual machines, 4 CPU, 2 gb RAM. They are based on Windows 2008 x64 SP2 Enterprise Edition.

Sql Server 2008 is used.

Apparently CPU of both IIS serers is constantly around 60-70%.

Now, my question, is the load of 60-70% acceptable and how could we possible bring that down to less % (maybe using only one IIS server)?

Assets can be up to 20mb, but on average, they are about 30kb. (the load of 60-70% is achieved with assets around 30kb).

The开发者_Python百科 data that gets saved with weborb is very small (2kb) and is just one object.