Im not the creator of the game.
But in generel firefox cannot run construct 3 games very well, it will get very laggy due to the engine itself and how firefox handles graphics.
I assume we're all here to improve, so this is just a recommendation for that.
When I start up Firefox and filter itch.io by Construct 3 games, all the ones I've tried so far work seamlessly, and nothing in the docs or forums I've seen indicate compatibility issues with Firefox (sorry if I missed this being documented somewhere as an issue).
I would start by looking into object pooling or similar patterns to reduce the number of objects or independent textures being created/destroyed every frame.
If you're sure Chrome is going to work fine, then while creating the project, I recommend you do all the testing in Firefox, and the first thing you add that makes it start lagging is where I recommend you start to optimize.
Reading my prior response made me realize how poorly it could come across.
I should clarify that I have no real idea why your game would work in other browsers or what the fix should be, my intention was to give an example of how I might approach the issue, short of changing engines.
Sometimes with text I assume my meaning may get across but miss an alternate interpretation, which in this case could be pretty condescending, sorry about that!