I think it's less about a performance loss and more about the idea that sanity checks may not be valid in certain circumstances. For example, the CSP checks might be invalid if you're using django-csp but also using a local version of `include.js` (which currently you shouldn't, but I've asked before and it's not necessarily invalid, just a bad idea right now as the API is changing a lot).

We could have a setting for disabling the sanity checks. Hm.