Microsoft is finally fixing the WSL2 bug that pushed developers to Mac and Linux

The fix, in plain terms

The post explains a real, specific optimization. Until now, every virtual device in WSL2 — the virtiofs mount for /mnt/c, the mount for /mnt/d, the network adapter — shared a single global SWIOTLB bounce-buffer pool, and under heavy I/O they all "queued into the same buffer, contending with each other." A new change gives each device its own DMA pool, which the author calls one of "the last remaining bottlenecks on the virtiofs path." The honest caveat is that the post offers no before/after numbers — it's described qualitatively — and the win only applies if you've opted into virtiofs (still off by default) and updated to a specific kernel build.

The thread reads as an exit interview

The technical detail mattered less to commenters than the years of accumulated grievance it finally addresses. The /mnt/c performance penalty is, in the thread's telling, a load-bearing reason people left Windows entirely:

"Proton, Copilot, and literally this single issue are what pushed people to Linux… WSL native filesystem performance gave devs that magical experience when they boot into Linux." — a developer on the exodus

Some had simply given up years earlier — one moved to Mac "about 7 years ago because of horrible WSL file system speed". And a recurring frustration was that this was tolerated for so long at all: both WSL2 and Docker-for-Mac filesystem performance are "so horrendously bad that you can just tank performance" versus a normal Linux box that's "3x better" for most projects. A practical note explained who's actually hit: people who run their projects out of /mnt/c "with zero clue of that implication."

The win is real, the timing is the story

Per-device DMA pools are a legitimate fix to a legitimate bottleneck, and file-heavy cross-OS workflows are exactly the ones that'll feel it. But the thread is the more interesting artifact: it's a list of developers who already voted with their feet. Microsoft is patching the wound; the scar tissue — years of people who switched to Mac or Linux and never came back — doesn't heal with a kernel update.