Merge branch 'perf/p2-contiguous-reads' into feat/p2-perf-coverage

# Conflicts:
#	CHANGELOG.md
#	docs/known-issues.md

docs/known-issues.md

@@ -9,7 +9,8 @@ deleting it.
 
 ## Concurrent and contiguous read performance (measured 2026-09-26)
 
-**Status:** open; one cause of the first bullet fixed (2026-09-26). Measured on
+**Status:** open for chunked full reads (one cause fixed 2026-09-26); the
+contiguous item is fixed (2026-09-26). Measured on
 tank with `concurrent_read` against h5py 3.16 / HDF5 2.0 (`BENCHMARKS.md`,
 "Concurrent reads"):
 - **Partly fixed 2026-09-26.** Full reads of chunked datasets from several threads
@@ -34,6 +35,12 @@ tank with `concurrent_read` against h5py 3.16 / HDF5 2.0 (`BENCHMARKS.md`,
   the `f32` copy of it, and a new buffer per decoded chunk).
 - Contiguous datasets read 4x slower than h5py on one thread (2.5 vs
   9.8 GB/s full, 0.12x for 256 x 256 hyperslabs).
+  **Fixed 2026-09-26** (not yet re-measured for `BENCHMARKS.md`): full
+  reads were dominated by 4 KiB page faults on the fresh output buffer,
+  which is now backed by transparent huge pages as numpy's is; hyperslab
+  reads copied the selection three times, element by element, and now copy
+  each contiguous run once, straight from the file into the output (see
+  `CHANGELOG.md`). The chunked-read scaling item above is still open.
 Values are correct; this is speed only.
 
 ## Silent wrong data found by the 2026-09-25 HDF5 audit