Glad you liked it.
I apologize that the how-to-play is unclear and visual cues are misleading.
The "performance issue" is consistent across all devices, because it is not actually performance issue. Instead, it is a race condition bug when entities spawn, interact and despawn. I will be honest I was not able to fix it due to "Skill Issue".
Shoot sound is bad I know... In fact I was totally lazy in terms of assets for this game. I do intend to develop a indie game that is not for game jams, so by then I will be more serious about finding quality gun sounds among others.