Windows 11 Dev Drive · ReFS

Small-file I/O gets an antivirus tax cut

A Dev Drive runs Microsoft Defender in asynchronous mode, so npm install, git checkout and bin/obj rebuilds stop paying a scan on every tiny file.

Scroll to see the numbers↓

Benchmark · 8,000 × 2 KB files

Small-file I/O: NTFS vs Dev Drive

Both volumes on the same NVMe — the only variable is Defender's scan mode (synchronous on NTFS, asynchronous on the Dev Drive).

▼39.6%
Total time saved across all operations
19,901 ms on NTFS  →  12,028 ms on the Dev Drive
C: (NTFS)
19,901 ms
Dev Drive
12,028 ms
Time per operation (lower is faster)
C: (NTFS) Dev Drive (ReFS)

How it was measured. Benchmark-DevDrive.ps1 — write/create, read, then delete 8,000 files of 2 KB each. Average of 2 timed runs, first discarded as warm-up. Both volumes on the same physical NVMe; a native (non-VHD) Dev Drive typically shows an even larger gap.  ·  Back to the repo ↗