I think caching may not be working on V4. When I create a site with caching enabled (ee site create www.easyengine.tk --type=wp --ssl=le --cache) and I run GTmetrix I get a certain result (see attachment)
When I delete the site and create a new one without the --cache flag the results in GTmetrix are totally the same. I would expect a (significant) difference. When I look at phpconfig() for the site without the cache-flag it states that Redis support is enabled. Isn’t that strange too?