I'm not convinced, the cache for the templates is a lazy cache, which means we always add the item to the cache, but we don't get items from cache unless `cacheTemplates` is true. In other words, having a `_cache` object attached to the view engine is not an issue, because when the accessor want to pick up a template and render it in the engine, it will not use that cache if `cacheTemplates` if not true.