diff --git a/loopy/target/c/codegen/expression.py b/loopy/target/c/codegen/expression.py
index caee73eb1c3320f03ceac66e55e8f5c0bfadbbc2..c111a02b75243b10de90b2d18d62e3759c575fa8 100644
--- a/loopy/target/c/codegen/expression.py
+++ b/loopy/target/c/codegen/expression.py
@@ -525,11 +525,17 @@ class ExpressionToCExpressionMapper(IdentityMapper):
 
             real_sum = p.flattened_sum([self.rec(r, type_context) for r in reals])
 
-            complex_sum = self.rec(complexes[0], type_context, tgt_dtype)
-            for child in complexes[1:]:
-                complex_sum = var("%s_add" % tgt_name)(
-                        complex_sum,
-                        self.rec(child, type_context, tgt_dtype))
+            c_applied = [self.rec(c, type_context, tgt_dtype) for c in complexes]
+
+            def binary_tree_add(start, end):
+                if start + 1 == end:
+                    return c_applied[start]
+                mid = (start + end)//2
+                lsum = binary_tree_add(start, mid)
+                rsum = binary_tree_add(mid, end)
+                return var("%s_add" % tgt_name)(lsum, rsum)
+
+            complex_sum = binary_tree_add(0, len(c_applied))
 
             if real_sum:
                 return var("%s_radd" % tgt_name)(real_sum, complex_sum)
@@ -569,11 +575,17 @@ class ExpressionToCExpressionMapper(IdentityMapper):
             real_prd = p.flattened_product(
                     [self.rec(r, type_context) for r in reals])
 
-            complex_prd = self.rec(complexes[0], type_context, tgt_dtype)
-            for child in complexes[1:]:
-                complex_prd = var("%s_mul" % tgt_name)(
-                        complex_prd,
-                        self.rec(child, type_context, tgt_dtype))
+            c_applied = [self.rec(c, type_context, tgt_dtype) for c in complexes]
+
+            def binary_tree_mul(start, end):
+                if start + 1 == end:
+                    return c_applied[start]
+                mid = (start + end)//2
+                lsum = binary_tree_mul(start, mid)
+                rsum = binary_tree_mul(mid, end)
+                return var("%s_mul" % tgt_name)(lsum, rsum)
+
+            complex_prd = binary_tree_mul(0, len(complexes))
 
             if real_prd:
                 return var("%s_rmul" % tgt_name)(real_prd, complex_prd)