Custom collision physic shape or collision walls actors for backgrounders?

geoascencio

So for some of my larger scene, I have maze-like levels with halls and rooms, and I find my self having over 20 invisible-unmovable actors that collide with the main character.
I wonder if I should just use a third part physics body editor to make a custom collision shape for the whole background image. Would this be a good idea?
Which would use more memory and cause the game to slow down??
Again these scenes are very large.