It's my understanding, having done benchmarks on file access on Windows, that NTFS itself is not the problem. It's old, but the revision of the on-disk structure that we use today hails from Windows XP, and it's about on par in terms of feature parity (and backwards compatibility, given that I can still read native NT 3.51 volumes on Windows 11) with ext4.
A lot of the weirdly bad performance comes from all of the machinery that Windows wraps around file access for things like filter drivers. As long as you don't, say, indiscriminately follow every CreateFile() with a CloseHandle() and instead treat handle closure like garbage collection, you can actually eke out pretty good performance.
That all said, yeah, Windows containers are less than great for what I'd argue is one strikingly glaring flaw: Docker container images are built from smss.exe upward. That makes them not immediately portable between ntoskrnl.exe releases.