I am attempting to extend the ContentOutputCache to play friendly with Visitor Groups. I found this blog post, and although it's 7 years old it does explain the problem and provides a potential solution: https://www.david-tec.com/2014/03/Enabling-output-caching-on-an-EPiServer-site-that-uses-Visitor-Groups/
Unfortunately, I can't seem to get this to work locally. Is there a recommended way of extending Episerver such that pages can be cached for performance but the site still leverage VisitorGroups for behavior based personalization?
Our caching implementation is based on that exact example. We worked with EPi directly to implement it. We needed to extend it further to take into consideration multi-site and multi-language, but it works nicely.
What bit isn't working for you?