I'm not 100% sure it is the database that is slowing this down.
it is likely a concurrent user issue, but even then I'm not sure where.
if you look at what gets done on each page load, the database is a small part of it, whereas the webserver does much more work...
would be very curious to see the output of an uptime on all the servers involved (I do hope that there are multiple servers, or else that would point to the issue at hand)