If there is "just" the demand for a large map, why does not somebody host a big standard map. That probably would perform much better ... Actually a BB sized map runs on standard even in 32 bit version, consuming (without convois) about 1.2 GB. Since the original routing of Knightly was not that wasteful, there must be something in very urgent need of improvement (or remove to tilt the balance to playability).
About download speed: I myself (in Japan) have 5 GB/s broadband (although only GB ethernet) at home, but since the Chinese "accidently" destroyed one important sea cable last year, all internet traffic is routed via the US. So typical ping is 326ms to Europe. Maintaining my servers on commandline feels like early 90ies again and modem speed. This will certainly affect download speed from Japan.