The game needs optimization.
Ah, it's probably the web version you're trying then? I've been looking into that recently. Apparently a lot of Godot 4 web games have this issue and it's due to browser + web standard shenanigans(to put ineloquently). I can't do much about it at the moment, and porting the game over to Godot 3 would be quite difficult. If you want to give this game another chance, try the standalone builds!
If it's not the web version you're having issues with but the downloaded one, if you could share some info about where the issues come up (whether it's the start of the game, or hitting enemies, or etc.), that would be helpful!
Alright! I managed to completely swap out the inefficient Scene Tile instantiation system with a GridMap implementation.
I had to completely remodel the floor and wall tiles. I also deleted some faces that weren't being used.
Here is the new specs! The upper Godot instance is actually the editor. I can't think of much else I can do at the moment so I'll just upload the build as soon as I can.
Although the memory is still at 200~ MB...