Multi threaded webserver vs single threaded
If the Web server is single-threaded and DB requests are synchronous (meaning the Web server is blocked while the DB request is being processed) then making it multi-threaded would help.
This would enable you to process multiple requests simultaneously. Your DB engine is probably quite good at that. However, right now you're not letting it to service multiple requests simultaneously because you have the Web server sitting right in front of it that only feeds it one request at a time.
We have a simple webserver for internal use that has only one duty: listen for requests, read them, and push the data in a database. The db and webserver are both located on the same machine. The db is a mysql-db and the server is a python webserver (BaseHTTPServer.HTTPServer) which runs single threaded. 
The problem is that two requests can't be handled at the same time. The question is, would it help to make the webserver multi-threaded (using django, cheryypy,..)? Intuitively, the webserver is only performing CPU consuming tasks so changing it to multi-threaded shouldn't help. Is this correct?