Octree Implementation in Mini Engine

Octree Implementation in huge 3D static space, to decrese the time bewteen frames in a small engine in comparison with a object collision detection done by check every player with every object.
Code:
https://github.com/r4z396/OctreeImplementation
My solution for this aproach about a huge 3D static space, taking in count that the most important optimization that must be done is decrease the time between frames, is an Octree implementation.
Results: I lose time in the initialization of the world and memory use, in exchange of a huge increase in performance of frame rate.
CPU: i7-6700HQ @ 2.60GHz Platform: x64
Initialization Time Average time between frames
Vanilla 3500.86ms 1370.25ms
With Octree implementation 13712.6ms 0.0386ms
Image source: https://developer.apple.com/documentation/gameplaykit/gkoctree