thank you for your reply, but, with firefox, the game went smooth and this started for a week or so and until then it played well. besides, a few days ago i tried chrome and the result is the same as firefox, also opera has the same behavior. i tried to contact the game devs and i'm waiting them to respond. thanks again.
see here
https://support.mozilla.org/en-US/questions/1002680?esab=a&s=&r=0&as=s
this was started by me when i thought the issue came from firefox. there is someone there that says it runs ubuntu or something and the behavior is the same. so, the os or browser has nothing to do with it, but, as you said, it's very likely to be from the devs side.