From db0b8b3445c0a6a387875cb1bfa12da0b88c3fe6 Mon Sep 17 00:00:00 2001
From: Bouwe Andela <b.andela@esciencecenter.nl>
Date: Fri, 15 Nov 2024 12:55:42 +0100
Subject: [PATCH 1/3] Use custom tokenization function for NetCDFDataProxy
 objects

---
 lib/iris/fileformats/netcdf/_thread_safe_nc.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/lib/iris/fileformats/netcdf/_thread_safe_nc.py b/lib/iris/fileformats/netcdf/_thread_safe_nc.py
index 3a556f5447..9956f1480a 100644
--- a/lib/iris/fileformats/netcdf/_thread_safe_nc.py
+++ b/lib/iris/fileformats/netcdf/_thread_safe_nc.py
@@ -327,6 +327,12 @@ def ndim(self):
     def dask_meta(self):
         return np.ma.array(np.empty((0,) * self.ndim, dtype=self.dtype), mask=True)
 
+    def __dask_tokenize__(self):
+        # Dask uses this function to uniquely identify the "array".
+        # A custom function is slightly faster than general object tokenization,
+        # which improves the speed of loading small NetCDF files.
+        return f"<{self.__class__.__name__} path={self.path!r} variable_name={self.variable_name!r}>"
+
     def __getitem__(self, keys):
         # Using a DatasetWrapper causes problems with invalid ID's and the
         # netCDF4 library, presumably because __getitem__ gets called so many

From bfbd62551ba52cc09d1667f4c036420f6a12d807 Mon Sep 17 00:00:00 2001
From: Bouwe Andela <b.andela@esciencecenter.nl>
Date: Wed, 11 Dec 2024 13:11:31 +0100
Subject: [PATCH 2/3] Add benchmark for files with many cubes

---
 benchmarks/benchmarks/load/__init__.py | 52 ++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)

diff --git a/benchmarks/benchmarks/load/__init__.py b/benchmarks/benchmarks/load/__init__.py
index a4dfb40d19..5c5a62a515 100644
--- a/benchmarks/benchmarks/load/__init__.py
+++ b/benchmarks/benchmarks/load/__init__.py
@@ -132,6 +132,58 @@ def time_many_var_load(self) -> None:
         _ = load(str(self.FILE_PATH))
 
 
+class ManyCubes:
+    FILE_PATH = BENCHMARK_DATA / "many_cube_file.nc"
+
+    @staticmethod
+    def _create_file(save_path: str) -> None:
+        """Run externally - everything must be self-contained."""
+        import numpy as np
+
+        from iris import save
+        from iris.coords import AuxCoord, DimCoord
+        from iris.cube import Cube, CubeList
+
+        data_len = 81920
+        bnds_len = 3
+        data = np.arange(data_len).astype(np.float32)
+        bnds_data = (
+            np.arange(data_len * bnds_len)
+            .astype(np.float32)
+            .reshape(data_len, bnds_len)
+        )
+        time = DimCoord(np.array([0]), standard_name="time")
+        lat = AuxCoord(
+            data, bounds=bnds_data, standard_name="latitude", units="degrees"
+        )
+        lon = AuxCoord(
+            data, bounds=bnds_data, standard_name="longitude", units="degrees"
+        )
+        cube = Cube(data.reshape(1, -1), units="unknown")
+        cube.add_dim_coord(time, 0)
+        cube.add_aux_coord(lat, 1)
+        cube.add_aux_coord(lon, 1)
+
+        n_cubes = 100
+        cubes = CubeList()
+        for i in range(n_cubes):
+            cube = cube.copy()
+            cube.long_name = f"var_{i}"
+            cubes.append(cube)
+        save(cubes, save_path)
+
+    def setup_cache(self) -> None:
+        if not REUSE_DATA or not self.FILE_PATH.is_file():
+            # See :mod:`benchmarks.generate_data` docstring for full explanation.
+            _ = run_function_elsewhere(
+                self._create_file,
+                str(self.FILE_PATH),
+            )
+
+    def time_many_cube_load(self) -> None:
+        _ = load(str(self.FILE_PATH))
+
+
 class StructuredFF:
     """Test structured loading of a large-ish fieldsfile.
 

From 9a1a14dff2d4024f747d7344617c836fc71f45b2 Mon Sep 17 00:00:00 2001
From: Bouwe Andela <b.andela@esciencecenter.nl>
Date: Wed, 12 Feb 2025 21:39:50 +0100
Subject: [PATCH 3/3] Add whatsnew

---
 docs/src/whatsnew/latest.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/docs/src/whatsnew/latest.rst b/docs/src/whatsnew/latest.rst
index 74d090a006..d9f0701a18 100644
--- a/docs/src/whatsnew/latest.rst
+++ b/docs/src/whatsnew/latest.rst
@@ -61,7 +61,7 @@ This document explains the changes made to Iris for this release
 ===========================
 
 #. `@bouweandela`_ made loading :class:`~iris.cube.Cube`s from small NetCDF
-   files faster. (:pull:`6229`)
+   files faster. (:pull:`6229` and :pull:`6231`)
 
 #. `@fnattino`_ enabled lazy cube interpolation using the linear and
    nearest-neighbour interpolators (:class:`iris.analysis.Linear` and