For this particular application, I simply cannot afford it. MyISAM is able to cache index and data separately, using it I can keep the whole index in RAM and website works great. I tried to convert to InnoDB, the result was 4x larger database and 20 times worse performance, mostly due to the fast that index and data gets the same priority for caching so it was killed by disk I/O. If this website was earning enough money to buy at least 4 x more RAM it might not be a bad idea. However, it this case I’d rather use Firebird - it has a similar memory footprint as InnoDB, but has much more features (*real* stored procedures and triggers that work without problems, ability to use table aliases in delete statements, database events functionality, better resistance to system crashes, etc.)