diff --git a/asv_bench/benchmarks/indexing.py b/asv_bench/benchmarks/indexing.py
index d8b1bf327294a..8058b347383a7 100644
--- a/asv_bench/benchmarks/indexing.py
+++ b/asv_bench/benchmarks/indexing.py
@@ -515,6 +515,18 @@ def time_setitem_list(self):
         self.df[[100, 200, 300]] = 100
 
 
+class SetitemObjectDtype:
+    # GH#19299
+
+    def setup(self):
+        N = 1000
+        cols = 500
+        self.df = DataFrame(index=range(N), columns=range(cols), dtype=object)
+
+    def time_setitem_object_dtype(self):
+        self.df.loc[0, 1] = 1.0
+
+
 class ChainIndexing:
     params = [None, "warn"]
     param_names = ["mode"]