diff --git a/jax_profiling/jit/datacube/delaunay.py b/jax_profiling/jit/datacube/delaunay.py
index 3d7918a..01ff97d 100644
--- a/jax_profiling/jit/datacube/delaunay.py
+++ b/jax_profiling/jit/datacube/delaunay.py
@@ -211,6 +211,11 @@ def jit_profile(func, label, *args, n_repeats=10):
 )
 
 with timer.section("dataset_list_load"):
+    # apply_sparse_operator: precompute the NUFFT precision-matrix preload per
+    # channel so per-fit curvature assembly uses the FFT-based sparse path
+    # instead of dense DFT for every source pixel. Unblocked by PyAutoArray#316
+    # (the Pmax > 1 extent-indexing fix); on Delaunay this was previously
+    # guarded with NotImplementedError.
     dataset_list = [
         al.Interferometer.from_fits(
             data_path=dataset_path / "data.fits",
@@ -222,7 +227,7 @@ def jit_profile(func, label, *args, n_repeats=10):
             # the JAX-traceable path is the goal, NUFFT (pynufft) is not yet
             # JIT-friendly.
             raise_error_dft_visibilities_limit=False,
-        )
+        ).apply_sparse_operator(use_jax=True, show_progress=False)
         for _ in range(n_channels)
     ]
 
diff --git a/jax_profiling/jit/interferometer/delaunay.py b/jax_profiling/jit/interferometer/delaunay.py
index 34c1d9b..4fec68c 100644
--- a/jax_profiling/jit/interferometer/delaunay.py
+++ b/jax_profiling/jit/interferometer/delaunay.py
@@ -212,6 +212,13 @@ def jit_profile(func, label, *args, n_repeats=10):
         raise_error_dft_visibilities_limit=False,
     )
 
+with timer.section("apply_sparse_operator"):
+    # Precompute the NUFFT precision-matrix preload so per-fit curvature
+    # assembly uses the FFT-based sparse path instead of dense DFT for every
+    # source pixel. Unblocked by PyAutoArray#316 (the Pmax > 1 extent-indexing
+    # fix); on Delaunay this was previously guarded with NotImplementedError.
+    dataset = dataset.apply_sparse_operator(use_jax=True, show_progress=True)
+
 n_visibilities = dataset.uv_wavelengths.shape[0]
 print(f"  Total visibilities: {n_visibilities}")