If your latency is generally a combination of # of routers, physical path, and network congestion between you and the destination. Locally number of hops dominates the latency. So if the old path is comcast > Level 3 > google then running a comcast > google line will lower your latency by removing Level 3's routers and probably proving a shorter path.

Bandwidth isn't literally width like a pipe of water. It is linespeed. That is why higher quality cables have higher bandwidth, even though packet transmission is completely serial. "wdth" is an illusion created by time division multiplexing, like multitasking/multithreading on a PC.