It looks like TalkingPointsMemo uses this same software in their comments. Here’s an example thread. There’s a whole lot less white space between posts there. And a whole lot less additional distracting crap in general.
If they can get rid of the unnecessary white space and the equally unnecessary clutter, we should be able to do that here, right? Pretty please? 
Never mind - I see we have about eight different themes available, and some of them are a distinct improvement in this respect.
It’s a convoluted path to get to where you can change themes, so someone else will have to describe how to get there.
Which theme did you find that reduces the whitespace? (To save me from having to try every one. I did play with the themes a bit but noticed that you have to save each one to get the page to update and you only see the theme settings page unless you go back to the threads in between each attempt.)
I’m currently going with Discourse Classic. The white space is still mostly there, but each post is in its own box which (for me at least) works better visually.
I think the default is either Graceful or Light.
Thanks, yeah that one is better!
The link in the OP executes on this page instead of opening a new tab or window; that should be changed IMO.
You can change the way links behave in your preferences. I set mine to open all links in a new tab.
Anyway, with the change in theme, I’d say this new board is at least tolerable. And if it means the end of the routine 502 and 504 errors, well, that’s a big deal.