ASV: Add additional to_csv benchmark (#44942)

Author: phofl

asv_bench/benchmarks/io/csv.py

@@ -98,6 +98,9 @@ def setup(self):
     def time_frame_date_formatting_index(self):
         self.data.to_csv(self.fname, date_format="%Y-%m-%d %H:%M:%S")
 
+    def time_frame_date_no_format_index(self):
+        self.data.to_csv(self.fname)
+
 
 class ToCSVDatetimeBig(BaseIO):