Does SQL Server Clustering Enhance Performance?
SQL Server cluster is a fault tolerance solution it has nothing to do with performance.

If you want your load on sql server to be shared , you should be looking at Replication or maybe log shipping, direct reporting calls to that replicated /log shipped server and keep application calls to the main server. 

If your data gets too large that no matter what you do, performance is still a problem, consider archiving data to a data warehouse, in your application database (OLTP database) only keep recent records (last 6 months).  Anything older than 6 months gets shipped to your data warehouse (OLAP database). 

The moral of the story is clustering your server isn’t going to give you any performance boost, consider an alternative option.