The problem isn't google using the bandwidth, it's exactly what the GP typed. ISP's (The very provider of the internet to your location...) throttles upload speeds.
That makes the upload speeds.... slow. That causes the problems you've mentioned, not the fact that google is using it.
So why, then, when I am using DBox, FileZilla, uTorrent, etc, etc, etc...etc it doesn't do this?
Google Drive is the only local upload client program that I've had this problem with. It works fine if I only use it via the web interface, so is it my browser that's keeping Greedy Drive in check? If so, why can't they upgrade their client to do the same?
Having the ISP unthrottle upload bandwidth would simply shorten the length of time that GD hogs the connection, not prevent it from doing so in the first place. It's like trying to water the garden with a damn firehose...