This is about un documented limit of your hosting provider
You have this solution
* create multi user for one database and select on at random whenever one call your site
* enable a good caching plugin
* switch to use sqlite as wp database; if you have a small site
* change your hosting provider and this is the real best of all solution
* many hosting provider that offer wp hosting they do not support real traffic on it, and put lots of undocumented limits.
if you plan to pay 4$/m you may try:
http://www.arvixe.com/coupons[
^]