I would manually run all the crons in the acp, I think this should be automatically cleaned up every hour, is it a very busy forum, or have you turned any of the cron jobs off.
It could potentially be due to a ddos, which I'm expecting to see more of now we are getting a new wave of bots hitting us
also, as asked already... if it's not a highly busy forum, and the crons look like they are running
Your server access logs should give you an indication of where / why this large amount of views occured