mono/mcs/class/System.Web/performance-and-tips

* Prefer String.Compare to changing case

	If you need to compare strings ignoring case, you should use
	String.Compare rather than calling ToLower on both. This
	avoids allocations.

* Prefer ToLower to ToUpper

	Apparently, ToLower is faster.

* Use the InvariantCulture

	InvariantCulture should be used for all "non-linguistic
	identifiers" (see http://tinyurl.com/9vqus -- the 2.0 string
	recommendations). It is faster and more correct.
	
	Some methods in the string class that you might not think are
	culture sensitive really are. The following methods are
	culture sensitive:

		- .CompareTo
		- .ToUpper
		- .ToLower
		- .StartsWith
		- .EndsWith
		- .IndexOf (string, ...)
		- .LastIndexOf (string, ...)
	
	The methods in System.Web.Util.StrUtils exist to make correct
	calls less verbose. They use the InvariantCulture.
  
* Size of controls 

	In controls, it is important to keep the size of controls
	small. Controls can be replicated many times on a page due to
	data bound controls. The more memory each control allocates,
	the more GCs we have to go through.
  
* Avoid extra fields

	There are a few techniques to save space in the number of fields.

* Use [Flags] enums rather than many bool's

	Each bool takes up 1 byte. If you use a flags enum you can
	pack 8 bools into the same amount of space.

* Use the Events framework

	Every time you say
	
		public event EventHandler x;
	
	it creates a field. Most of these fields never get
	used. Control has a property called Events which holds a
	linked list of events that get created. Thus, events only take
	up space when one uses them. An example of using this:
	
		static object event_name_blah = new object ();
		....
		public event EventType EventName {
			add { Events.AddHandler (event_name_blah, value); }
			remove { Events.RemoveHandler (event_name_blah, value); }
		}
		....
	
	If your control has a OnEventName that invokes EventName, you
	have to do:
	
		EventType deleg = (EventType) Events [event_name_blah];
		if (deleg != null)
			delege (arguments);
	
* ViewState

	Keep the view state small.
	
	Remember that whatever gets stored in ViewState after tracking
	starts needs to be sent over the wire.
	
	Store in ViewState the minimum amount of objects needed to
	restore your state.
	
* Store optimized classes.

	It is important to store things in terms of primitive types
	(int, short, bool, byte, string), Hashtables, ArrayLists,
	object arrays, and specially optimized types (Unit, Color,
	Pair, Triplet) when saving viewstate. Otherwise, things will
	have to be put in a more expensive format over the wire.
	
* Store int values rather than enums.

	If you store an enum, the fully qualified name to the enum
	needs to be sent over the wire. Cast the enum value to an
	integer when storing it in view state. Keep in mind that

		object o = 1;
		MyEnum e = (MyEnum) o;

	Works, so you don't need any complex code when getting the
	stuff back.

* Return null in SaveViewState when possible

	For example, if you normally save the state of your 3 children
	to a triplet, but all 3 values are null, return null, rather
	than new Triplet (null, null, null);
	
	Often, doing this allows the framework to avoid saving
	anything about many layers of controls in the viewstate.

* Cache in variables

	Accessing a property in the controls usually means reading
	from ViewState.  Try assigning property values to local
	variables if they are going to be used more than once and are
	known to not change while a given method runs.

* Handle Enabled and Visible.
	
	If Enabled is false, your control should not handle any
	postback.  If Visible is false, your control does not render
	anything (but still keeps its state). Usually the parent takes
	care of that.