How to force all traffic to HTTPS on wordpress multisite?

I am struggling to get a way to put all traffic to https for my wordpress multisite. I have tried several plugins. Some gave me an infinite re-direct loop.

One called "wordpress https" worked but after my site slowed right down I ran P3 profiler and it showed me that my SQL queries had gone from 112 per visit up to 2070 per visit with the plugin enabled which is ridiculous.

What is the best way to force everything over HTTPS?