How slow is Reflection

Question

I recently created an interface layer to distinguish the DataAccessProvider from our Business logic layer. With this approach we can change our choice of DataAccessProvider

Answer 1

I thought I'd do a quick test to demonstrate how slow reflection is compared to without.

With Reflection

• Instantiating 58 objects by iterating through each of their Attributes and matching

• Total Time: 52254 nanoseconds

  while (reader.Read()) {
      string[] columns = reader.CurrentRecord;
      CdsRawPayfileEntry toAdd = new CdsRawPayfileEntry();
      IEnumerable rawPayFileAttributes = typeof(CdsRawPayfileEntry).GetProperties().Where(prop => Attribute.IsDefined(prop, typeof(CustomIndexAttribute)));
      foreach (var property in rawPayFileAttributes) {
          int propertyIndex = ((CustomIndexAttribute)property.GetCustomAttribute(typeof(CustomIndexAttribute))).Index;
          if (propertyIndex < columns.Length)
              property.SetValue(toReturn, columns[propertyIndex]);
          else
              break;
      }
  }
  

Without Reflection

• Instantiating 58 Objects by creating a new object

• Total Time: 868 nanoseconds

      while (reader2.Read()) {
          string[] columns = reader2.CurrentRecord;
          CdsRawPayfileEntry toAdd = new CdsRawPayfileEntry() {
              ColumnZero = columns[0],
              ColumnOne = columns[1],
              ColumnTwo = columns[2],
              ColumnThree = columns[3],
              ColumnFour = columns[4],
              ColumnFive = columns[5],
              ColumnSix = columns[6],
              ColumnSeven = columns[7],
              ColumnEight = columns[8],
              ColumnNine = columns[9],
              ColumnTen = columns[10],
              ColumnEleven = columns[11],
              ColumnTwelve = columns[12],
              ColumnThirteen = columns[13],
              ColumnFourteen = columns[14],
              ColumnFifteen = columns[15],
              ColumnSixteen = columns[16],
              ColumnSeventeen = columns[17]
          };
      }
  

Albeit, not completely fair since the reflection also has to retrieve a specific attribute of every property 58*18 times on top of creating a new object via reflection, but it at least provides some perspective.