Most european countries have connections with more bandwith and less base latency for cheaper than the US, it's not a connection issue. If there was an issue it's that the repo itself is hosted on the other side of the world, but even so the sidenote itself is odd.
I wouldn't say it's odd at all - it's basically what's justifying actually trying to solve the problem rather than just going "huh... that's weird..." then putting it on the backlog due to it not being a showstopper.
This sort of thing has been a problem on every project I've worked on that's involved people in America. (I'm in the UK.) Throughput is inconsistent, latency is inconsistent, and long-running downloads aren't reliable. Perhaps I'm over-simplifying, but I always figured the problem was fairly obvious: it's a lot of miles from America to Europe, west coast America especially, and a lot of them are underwater, and your're sharing the conduit with everybody else in Europe. Many ways for packets to get lost (or get held up long enough to count), and frankly it's quite surprising more of them don't.
(Usual thing for Perforce is to leave it running overnight/weekend with a retry count of 1 million. I'm not sure what you'd do with Git, though? it seems to do the whole transfer as one big non-retryable lump. There must be something though.)
