Cache features in doc2feats

spacy/_ml.py

@@ -10,7 +10,9 @@ from thinc.neural._classes.resnet import Residual
 from thinc import describe
 from thinc.describe import Dimension, Synapses, Biases, Gradient
 from thinc.neural._classes.affine import _set_dimensions_if_needed
+
 from .attrs import ID, LOWER, PREFIX, SUFFIX, SHAPE, TAG, DEP
+from .tokens.doc import Doc
 
 import numpy
 
@@ -167,8 +169,13 @@ def zero_init(model):
 def doc2feats(cols=None):
     cols = [ID, LOWER, PREFIX, SUFFIX, SHAPE]
     def forward(docs, drop=0.):
-        feats = [doc.to_array(cols) for doc in docs]
-        feats = [model.ops.asarray(f, dtype='uint64') for f in feats]
+        feats = []
+        for doc in docs:
+            if 'cached_feats' not in doc.user_data:
+                doc.user_data['cached_feats'] = model.ops.asarray(
+                                                doc.to_array(cols),
+                                                dtype='uint64')
+            feats.append(doc.user_data['cached_feats'])
         return feats, None
     model = layerize(forward)
     model.cols = cols