Least costly alternative to GetPartBoundsInBox()

I don’t really need a table of objects as much i just need collision detection. I thought of using blockcasts but they’re a bit janky.

Part.Touched:Connect(). ??? If that’s what you want

What you could do instead is just measure the distance the objects are from the box.
Lets say your trying to figure if players are inside a box. What you can do instead is just measure the magnitude(distance) the players are from the box position and if its less than let says 30 units then it detects it as inside the box. If this is not what you want then I apologies, could you specify more on what your trying to do?