I downloaded your game. I took a 2 hour nap and I come back to my laptop being incredibly slow. I deleted it and several other things and it was still slow. your game is the only thing I downloaded all day. I had to factory reset my laptop to get it back to normal. its the only logical explanation
Sorry that happened to you, but the file is in the form of .zip, AFAIK, downloading any zip file is safe. Even after you extract the files inside, it'll still be safe, it'll only become unsafe if you run any of the files inside it, that's what google says anyway.
Maybe your laptop has a program with auto background update feature enabled and download an update that's causing the slow. Or, once I have a shitty laptop that download windows update and it's taking all the Disk Percentage (In the Task Manager, don't know what it actually is) and making it really slow.