Short quiz: Performance bottleneck for <math>-using pages is ... a) texvc b) latex c) database
The answer is of course c. One query is done for every occurence of <math>something</math> to check if it's cached. Usually it is, and neither texvc nor latex is run.
The solution would be to make only one such query per page, and if something's missing run texvc only once and pass all math formulas to it, and then update database in single INSERT query.
But that has low priority for me - it's pretty fast as is, and no Main Page uses <math>.