Octree build time crashes page for complex mesh

Question

Using the standard three.js FPS example of octree implementation with a more advanced mesh, crashes the page on load.

My first idea is to write a few functions to save the octee data to a file, then load it, to avoid the extra computational time, such as the following added to the example, which is slightly edited:

this.chootify/*save as object that can be stringified*/ = () => {
    return ({
        triangles:this.triangles,
        box:this.box,
        subTrees:this.subTrees.map(k=>k.chootify())
    });
};


this.load = (awts) => {
    this.triangles = awts.triangles
    this.box = awts.box
    this.subTrees = []
    if(awts.subTrees){
        awts.subTrees.forEach(k=>{
            var aw = new AwtsOctTree(k.box)
            aw.load(k)
            this.subTrees.push(aw)
        })
    }
}

and then I was planning on loading it in a background thread.

However I didn't realize that even for a fairly simple building mesh, the octree file would take up 230mb of space when stringified (example: run functions to worldOctree from console to test).

When using a more complex mesh with stairs etc. it completely crashes the web page using the standard build-on-runtime method.

I have no idea how to optimize this, any thoughts?