diff --git a/downloads-generation/models_class1/GENERATE.sh b/downloads-generation/models_class1/GENERATE.sh
index a63b17de22b294eae23970d75fde2c8c7b2166ac..2722c9fabf599ad24c07a3e6ff055d11d187dcc9 100755
--- a/downloads-generation/models_class1/GENERATE.sh
+++ b/downloads-generation/models_class1/GENERATE.sh
@@ -38,7 +38,7 @@ time mhcflurry-class1-train-allele-specific-models \
     --percent-rank-calibration-num-peptides-per-length 1000000 \
     --min-measurements-per-allele 75 \
     --train-num-jobs 0 \
-    --calibration-num-jobs 4
+    --calibration-num-jobs 1
 
 cp $SCRIPT_ABSOLUTE_PATH .
 bzip2 LOG.txt
diff --git a/mhcflurry/class1_affinity_predictor.py b/mhcflurry/class1_affinity_predictor.py
index 88c807afcd3f2a35bf4a8e0c6b3422eee93d19a2..7f0d248f4c409812d5685f2eb951d02dab871c7c 100644
--- a/mhcflurry/class1_affinity_predictor.py
+++ b/mhcflurry/class1_affinity_predictor.py
@@ -933,6 +933,10 @@ class Class1AffinityPredictor(object):
 
         if worker_pool and len(alleles) > 1:
             # Run in parallel
+
+            # Performance hack.
+            self.neural_networks[0].peptides_to_network_input(encoded_peptides)
+
             do_work = partial(
                 _calibrate_percentile_ranks,
                 predictor=self,