C# performance notes

• for v.s foreach
  1. for loops on List are a bit more than 2 times cheaper than foreach loops on List.
  2. Looping on Array is around 2 times cheaper than looping on List.
  3. As a consequence, looping on Array using for is 5 times cheaper than looping on List using foreach.
  4. LinkedList only allows foreach loops, as it would take quadratic time to loop a LinkedList through indices.
  5. Looping overheads: for < foreach; Array ~ List < ArrayList < LinkedList
• Everything stored in an ArrayList is an object. So be careful of the boxing/unboxing overhead.
• String concatenation overheads are negligible outside loops.