Is it possible to use the main ticking function?

I have multiple AActors that do quite a lot in their tick threads, none of which would interact with another AActor.
I am wanting to update these variables using Multithreading.

In other words, I’d like to have the main tick call a function in one class only, and that class to use multithreading to update all my AActors information.

I understand, but am always learning, multithreading and how to implement that part, but do not understand how I can use the main tick thread.

You’ll face many problems trying to get another thread to “tick” your Actors. The Actor class is built up to be run in the game thread and get their Tick() call via a system within that.

The more direct approach is to start figuring out what in our Actors Tick function is causing you to have performance problems.

You are correct that tick is expensive but multithreading is almost never the solution when it comes to problems like this. Not only is multithreading difficult, as you have to factor in the extra layer of issues to solve when using threads, use of mutex (lock / unlock), you are thinking on doing this in a class (AActor) that is governed by a completely different thread (game thread).

All this is to say that multithreading isn’t going to be some easy-to-use fix for the problem you are facing. You are going to add much more work - if it is even possible to do within UE4, in the context you want to - to solve what is effectively a optimization problem.