Killing Actors / Objects to Maximize Performance?

I have a RUNNER game, but there are moving characters as obstacles, as well as rigid bodies like boxes, etc.
As the player runs through the map (which is a hallway), I want to set a timer to REMOVE all characters and
objects that pass by him. I’ll know the amount of time it takes before the objects should be removed, so can I
somehow set a timer to do this? By eliminating the objects, characters and even parts of the map as well, I want to maximize performance and only focus on what’s in front.

ALSO, can I generate objects or parts of the map in front of him? It will be very dark, so he wont be able to see
far ahead anyway, and I want to be able to add the objects and then remove them at certain timers so that he is rendering the map and everything I’ve done in it as he walks through.

Tappy Chicken does it with the moving obstacles and the old items are removed via a vector coordinate.
Also, in

they just place a large volume behind the character and everything that overlaps gets destroyed

Awesome!! thankyou