I'm not a proffessional in this, but I have been learning about networking for 2 years now.
What you can do is run a test by yourself.
1. Go to your windows search bar, type in CMD or command prompt, open it up.
2. When it opens, write as such: ping 8.8.8.8 -t Ping is a command in networking that just sends a single packet to a destination and shows how much or if all the packet got there. 8.8.8.8 is the public google server that you can ping to. And -t makes sure that it goes until stopped.
3. Then just leave it on whilst you play (it won't cause any noticable lag by itself) or while you don't play.
4. Monitor when and how much it fluctuates (goes up or down in time miliseconds).
5. Then you can check what programs you had on or maybe if you might have some possible malware on your system. You never know.
Also, to close it, you can press the X on top, but it's not recommended, better stop it and then press X by doing CTRL+C, then close it off.