So I installed on our website (which was currently getting a "F" on GTMetrix) and did not expect much.

I have used several speed improvement plugins before and most work some, but require a fair amount of effort and testing. Our site has a lot of plugins installed - I generally will test anything we buy on it to see if there are issues, so the site has become a pretty good test bed for plugin compatibility.

Rabbit loader installed no problem, activated it, and site broke immediately. Great. Now I will have to reinstall the site and DB from a backup because who knows what this plugin has broken. Spacing issues, JS issues, CSS issues... but I also noticed that a few of the pages did work and look fine. That confused me a little, why could it handle some pages, but not others?

Decide to give it a couple of days to sort itself out (read some reviews here that said it may take 48 hours to get smoothed out).

I am now really impressed - over the next 2 days the site started working - everything back in place and functional. GTMetrix score has gone from an "F" to an "A" (never been able to get it to an "A" before with any speed optimization plugin).

My only complaint left is they need to increase the limits on the highest plan so an agency use this on lots of sites for a real workout. That's the next hurdle - can it be sustained?

Right now, I would say this is an absolute 'do not miss' deal (and hope for some higher limits).