server load

i run about 25 wordpress sites on shared hosting. i have a lot of plugins, and do use caching plugin.

webhost is teling me the mysite.com/index.php is causing excessive server load (50-80%). The odd thing is that these are not busy websites – most gets 100 pageviews a day.

I am planning on moving to a dedicated server – but I want to know what tweaks I can do to redcue load.

I heard wp-cron.php can be an issue too. Any help would be appreciated.