So I did some tests with CKAN locally, downloads always max out my connection, (probably) uncached or not. Time from first SYN to the start of the actual file transmission seems to be around 0,8 seconds, slightly less when cached. I think that's okay, GitHub looks to be similar.

I also testet with wget from my VPS which has a far higher bandwith available.
An big file with `--no-cache` was around 18 MB/s = 144 Mbit/s.
The same file allownig the cache then was 63 MB/s = 504 MBit/s.
I think wget is limited to HTTP/1.1
Using curl for HTTP/2 gives the same speed.

Might vary during prime time and with mutliple connections simultaneously, but I couldn't find anything majorly underperforming.