Subnetting allows to isolate traffic?

[Kahlo kahlow]

Hi, if I setup a subnet in my home and I've separated myself from other computers and I, for example, am taking all the bandwidth for my subnet will others connections be dropped? I've just learned about it a bit on school and I don't know if I have the right idea of it. I got really interested when the teacher said that it allows for better performance when many devices are connected. Instead of them being all in 1 network, you divide it and then improve your connection.

 

[USAFRet]

No.
Everything still flows out the same router, to the same ISP, with the same connection speed.

It only sort of helps with internal communication between devices.
Device A talking to Device B on Subnet 1, does not impact Device X and Device Y on Subnet 2.