I think, what you are looking for is to split the load between all your mysql servers.
Connector/NET does not currently support load balancing by itself (we will be providing a built in facility in release 6.7).
Currently all database request from Connector/NET will go to the server 'localhost', while the other just mirror the changes.
So your current options are:
a) Deploy MySql clustering, which provides transparent load balancing for the clients.
b) Implement load balancing yourself.
c) Research more in your actual performance problem, you can try Enterprise Monitor:
http://www.mysql.com/products/enterprise/monitor.html
d) If only the web app accesses the web server, you can change to master-slave replication.
There are some standard questions to answer when working out replication performance issues (if that is the case), see:
http://dev.mysql.com/doc/refman/5.1/en/replication-solutions-performance.html
http://dev.mysql.com/doc/refman/5.0/en/faqs-replication.html.
Also, are you using MySql 5.6? there are huge performance improvements in this version, and just made GA.
Can you provide more details in your case? As you may see there are many things to check here, it depends on your specific requirements.