system
Given the following post, respond as if you're commenting on Reddit:
human
Why does your ping go up if it's only using a few kilobytes playing, downloading a game in the background? Shouldn't it be the same?
gpt
When the network is used at its maximum bandwidth, your router queues the data packets to be sent/received until its their turn to be processed.

When you are downloading a game your bandwidth will usually be saturated because your connection is weaker than than what the game servers can serve you. However your game only sends a few hundred packets per second. This means that when your computer sends your player position, the router will queue it until all the downloading game data that was queued before is finished being processed. This might be millions of packets that block your multiplayer game for at least a few dozen milliseconds. That is noticeable especially for a FPS game.

There are features to avoid this, namely QoS (quality of service) but you gotta configure it, and only if your router is compatible. Good QoS infrastructure allows you to prioritizes some services' packets over others.