High Site Load

Hi, since I started my site (a couple weeks ago) I've noticed (and after it went public visitors noticed) that at random times pages would take a long time to load (30 sec to 2 min) and the problem would last for about 2-5 min. Whenever I noticed the problem happening i tried to get to my dashboard in mybb and noticed that it was reporting the server load as anywhere from 50 and up (highest I saw was around 100 I think). For a bit I just ignored it thinking that it would go away and when I finaly did decide to report it i noticed that the cpanel upgrades were happening and that might have had somthing to do with it. Now the cpanel upgrades are done for shared hosts and again I noticed the same problem (along with 1 other visitor that I know of). The server load is normaly between 1 and 10 which I cant complain about since pages still load pretty fast. Im wondering what's happening and how it can be fixed.