Hello, I'm an experienced database programmer/designer/architect (more than 10 years of Oracle, mysql and postgresql) from Russia. I have a rich experience in databases (from small to huge data warehouses). I'm good in administration, query optimization, plsql programming overall database tuning.
On one of my prevous jobs i've tuned mysql database, it was done properly and the client was happy with it. I will surely help you with vtiger and tell you some other steps to increase the overall performance of Vtiger and mysql server in general.
Best regards,
Andrey Kropachev