I am using multisite. I notice the cron is using alot

I am using multisite. I notice the cron is using alot of resources so i want to make all my sub site cron disabled. then i control it myself for all my site. it would be the same frequency and the same time vs cron activated each time a visitor visit a site. so how can i do that.

i seen this solution but have yet to try.
http://www.lucasrolff.com/wordpress/why-wp-cron-sucks/