I managed to replicate this with BAD being about 20 MB/s and good being about 65 MB/s
So it happened somewhere in the 1.40 development cycle.
I ran git bisect and it came up with this commit as being the problem one (as I expected!)
07f20dd1fd6f89b9ebdefdc8964a8e9ee9aa9892 is the first bad commit
Author: Fabian Möller <email@example.com>
Date: Wed Jan 24 00:46:41 2018 +0100
drive: migrate to api v3
:040000 040000 aad5e99c16dab297c5f79c505bb4d303d2497953 35a6b83de5afb909d3f83c9dfc29b9c2d7c20247 M backend
The difference appears to be that for v2 vs v3 is that we are downloading files from different endpoints:
rclone is downloading files the recommended way with the v2 API as far as I can see.
@B4dM4n - any ideas why the v3 API should be slower for downloading files?