Confirmed Netgames can also lag if you hold the window bar with your mouse

[Panda.]

You can just go to windowed mode. Hold the window bar (and don't touch the game, so the mouse will be stuck in the game and won't get out) for like 5 seconds. You will notice that the server is going to be frozen, the server will be completely lagged until you stop holding the bar. and any player won't be able to move because of lag of course.

And down there. Well, I don't know if this one looks like a bug. Just download a file from the server and do the same bug without ESC the download. The downloading wad will be stopped to continue download. but I still don't know why it made the internet downloading speed (internet status in the right of the gif photo) got little confused. but anyway you can still download it when you stop holding the bar. and the internet downloading speed will continue regularly.

 

[Monster Iestyn]

This one I've heard about a few times now. I'm not sure how to fix it though, unfortunately.

 

[SteelT]

Nothing can be done about that atm, it's due to how Windows works.