Me opening and closing this game on opera GX with hardware acceleration disabled. Idk how this is even possible for a browser game. It does not drop back down after the game has loaded, just keeps CPU at 100% consistently.
There's some performance improvements coming in a future patch (I'm hoping to get this patch out in the next week or so) that should help with things like this.
I generally recommend for people to have hardware acceleration on when running HFI in the browser, but I have also seen other reports of high CPU usage like this so I will continue to investigate.