The Q3D plugin is probably better written than this one. The freeze you are experiencing might be due to a lot of vectors being created. Out of ignorance at tge time, I did not apply some javacsript best practices on memory management.
Reken : yes, I created the scene using coppecube (the version from 2013 I think). I don't have the latest version of coppercube (expensive) but I would guess the problems you are seeing are due to the copperlich.js library used in the plugin being too old for your scene. If you know javascript, You could try replacing the copperlicht library in the plugin with the library that gets exported in your coppercube scene (i think the file is called copperlicht.js)