Not sure where you see the condescending manner in that thread. Honestly having read about this storm-in-a-teacup in various discussions without having previously read the thread that started it, it all seems remarkably mild and polite compared to expectations.

At the end you can see Casey is getting frustrated and doesn't really understand the WT team's responses, or why they're making a big deal out of it. The WT team in the meantime clearly feel they have higher priorities than raising performance in their legacy code, don't relish tossing their rendering pipeline to make a new one, and don't understand why Casey is so focused on performance. But they're definitely trying to find some mutual understanding and Casey is clearly trying to help them. There are way worse programmers-butting-heads threads out there.

Here's a controversial thought: the reason this blew up in such a big way isn't really to do with any of the people involved or their tone on some random GH issue but rather what this says about Microsoft and the general decay of the Windows platform. That frustration is widespread and totally understandable. The Microsoft devs on that thread all come across as very nice and reasonable people, but they also come across as inexperienced and out of their depth. This problem is not unique to that team. Microsoft are charging good money for this stuff (not WT directly but Windows as a whole). Many, many people are forced to deal with Windows whether they want to or not and end up having to deal with poor implementations even if they'd rather be using Linux or macOS.

The WT devs are IMO doing way better than the average dev working on Windows - they engaged seriously and honestly dev-to-dev, they admitted when they were wrong, they improved the product, and they've even given credit to the people who embarrassed them in public. If only everyone were so good natured!

I won't say which area because this is my anon account and I reported some bugs publicly but I've recently been dealing with a different Windows team (as an outsider) and smacking right into the exact same problem. The task their subsystem handles is a very easy one and yet it's filled with critical bugs. We're not even talking performance here but the basics like data corruption bugs, hangs, absurd security flaws, broken APIs, over-complicated file formats, the works. The actual feature spec is fine - whoever designed it at a high level did an OK job - but the implementation is just very poor. It's clear that the devs assigned to it are overwhelmed and seem to lack senior people who can catch basic mistakes during code review. Also even though this subsystem doesn't need high performance they're writing it in C++ instead of .NET, which is certainly making their lives harder. Unfortunately the team is like the polar opposite of the WT team. They don't engage with their user base, only via clueless devrel PM types who can't understand anything they're being told. The relevant systems aren't open source. They don't backport things. They don't communicate. Their docs are flaky, often advertising features that aren't even shipped yet or don't actually work. They make sudden decisions out of the blue that screw their users. Bug reports tend to get met with a stock response asking for submission of logs which are invariably then either "lost" or never heard about ever again.

It's clear that the Windows org has lost the ability to execute. It feels like the start of Atlas Shrugged, where everything is slowly falling apart and nobody can quite put their finger on why. Yet, we are stuck with it. There is a dire lack of competition in the desktop OS space.