Accelerating distance calculations with a QuadTree

#1
Let every object store their last distance

#2
Update realy close objects distances every frame

#3
Update close objects distances every 5fth frame

#4
Update objects distances far away every second

There you have it, x16 in speed!

you could store the distance from a patch of your quadtree to the camera and use that distance for all objects on that patch.

regards,
m4gnus