The issue with things like caching the active posts, is that this is a report of sorts, built on the InstantASP framework. If we look to try and clean this up ourselves, it interferes with upgrades. We have an upgrade set for the 2017 v of the forums (we're on 2016.3, I think), but we've delayed this as some other work is in progress.
Once we upgrade, we can look at it, but we like to submit this stuff via pull request to the vendor and have them incorporate it in an upgrade. That can be a bit of lobbying/negotiation with them, though I'd hope this would be easier to add than some other things we've proposed.