Crash - OnBecameVisible OnBecameInvisible & Mesh distorsion

Hi guys, I have a Crash issue.

I'm twisting meshes at runtime in my application so it fits to a curve that I drew in the editor. Here's an image of what's happening with a few comments :

On the top-left side, you got a prototype (a railroad in this example). On the top-right side, there is some piece of network I drew. And at runtime, you got the result from the bottom of the image.

I used to have those objects drawn in a Manager that looped over them every few frames to check if it had to delete/draw something. But I wanted to optimize my code using the 'OneBecameVisible' & 'OnBecameInvisible' methods because I'm starting to have huge number of objects to draw and I spend more time wondering which I should draw/delete than actualy drawing/deleting anything.

So the idea is that each prototype that must be drawn and twisted along the network, there is a box (an invisible stretched cube) that bounds the space in which the prototype is gonna be placed. Also I'm using a "IsBusy" bool to avoid concurrent drawing/deletion, etc.

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So how this is drawn at runtime :

• Everytime the box triggers the OnBecameVisible :

While(IsBusy), wait. Set IsBusy to true, instantiated prototype (or get it from a pool if any), compute the vertices distorsion, place the mesh, set back IsBusy to false.

• Everytime the box triggers the OnBecameInvisible :

While(IsBusy), wait. Set IsBusy to true, deleted the object (or release it in a pool for further usage), set back IsBusy to false.

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Everything works fine as long as you don't try to turn back several times or move forward and backward "too" fast. But when you do, it seems that the OnBecameVisible & OnBecameInvisible triggers in a way that makes my editor crash. I made some tests using only one prototype and I can make my editor crash nearly every time I turn back several times quickly. I added logs everywhere to track down if I didn't messed up my logic with my IsBusy boolean, everything looks cool... I also tried adding logs to track down a potential null ref (even though I don't think this could have lead to a crash), still nothing...

I'm out of options in my code. I'm suspecting the OnBecame(In)Visible methods to be the cause of my crashes. Does anyone have a lead ?

Sorry for that wall of text, I wanted to be clear and I find it quite hard to be clear and concise. Sorry for my english as well.

EDIT : Okay, I never had this before, it seems the editor crashes even when I turn back slowly... I'm even more confused...

EDIT 2 : I migrated my code to the Update function so that the OnBecame(In)Visible methods are not used anymore. Same result. I'm starting to think this is scene/cache related as I never had those troubles before...

EDIT 3 : Ok, fixed it. My code was working perfectly fine. The bug I wanted to correct appeared when an intern of ours added some "fix" in my code. Somehow, he managed to destroy my whole test scene & test prototypes. Even when I reverted his modifications, I could not make anything work again. I'm gonna break his both hands tomorrow, this won't happen again.