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Apparently, the cause of the long standing windows disk IO problem was discovered a month or so ago, and MS were said to be working on a fix.

Whether it'll be constrained to Win 11 is yet to be seen.

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That's interesting. A project at work is affected by Windows slow open() calls (wrt to Linux/Mac) but we haven't found a strong solution rather than "avoid open() as much as you can".

It's likely Windows Defender, which blocks on read I/O to scan files. Verify by adding a folder to its exclusion list, though this isn't helpful if it's a desktop app. The difference is most noticeable when you're reading many small files.

Really? Where did you hear that? Conventional wisdom is based on a post by an MS employee years ago that described the performance issues as architectural.

MS does have something called "dev drive" in Win11. Dev Drive is what ReFS turned into and is an entirely different filesystem that isn't NTFS, which is better optimized for UNIX-style access patterns. The idea is that core Windows remains slow, but developers (the only people who care about file IO performance apparently) can format another partition and store their source/builds there.

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