The libmysql that I included with the CSMySQL example was the latest that worked without crashing the engine/plugin last year. When I was trying to get it working again I just tried any libmysql that I could find. Could be that you actually need a previous version or might be that it works with later release also. Not really sure about that though.

Have to say that my demos are very basic and not require heavy load on the database, but I do know that in your case the database connections must be persistent. If I would put a lot of query for the dll to handle it will require a wait(1) to allow the task to complete, at least that's what I thought read somewhere in this topic.

Anyways I think it's best to rewrite with current sdk from http://tangentsoft.net/mysql++/