Yay! I managed to get it to work now - at least the first couple of thousand blocks are downloading really fast now.

What's strange is that I am sure I had checked out the master branch the last time I tested it ...

So ok, I think we can say now: with alpha 53 (ga4405760) the problem seems to have been fixed.

I think if we finish testing successfully, gjhiggins deserves to get the bounties that have been announced some weeks ago by various community members for the "working Windows wallet" and the "fixing of the most annoying bugs" (see OP for the exact messages where they were announced).