Continuing from ASP.NET Performance Tips Part 1 we now conclude with Performance Tips 26-50.

26. Batched Queries:

Queries can be used in a batch and thus network traffic can be reduced: Here is an example:

“Select EmpNo, EmpName, EmpAddress from Employee”;
“Select DepNo, DeptName From Department”;

From the above two queries it seems that there will be database hit twice .

Both the above queries can be executed in batched form and a single database hit will occur as follows:

“Select EmpNo, EmpName, EmpAddress from Employee; Select DepNo, DeptName From Department”;
27. Use IIS Compression

Page size can also be reduced using Http compression in IIS. Compression tool can also be used to reduced the size of rendered content.

28. Normalization

We should follow normalization rules in database table design but over Normalized tables can cause  excessive joins for simple requirement. We should not make excessive joins for performance overhead and hence it is better to normalize only as much as required keeping in mind the performance issue.

29. Efficient Coding

While coding we should keep in mind the below issues which are potential performance drains:

1.       Avoid use of Finalize method unless it is absolutely necessary.
2.       Make a class sealed if inheritance is not required.
3.       Avoid calling GC.Collect();
4.       Use X+=1 instead X=X+1 to avoid evaluating X twice;
5.       Use overloaded methods instead of different method names where possible.

30. Define The Scope of An Object

Defining an object’s scope properly increases efficient memory management and thus improve performance. We should keep the object scope at a lower level instead of a global level if possible because the garbage collector works more frequently on short lived object .

31. Using Loops

We should keep in mind while using loops in our code:

1.       Better to use for a loop instead of foreach.
2.       Do not create objects inside loop if not required absolutely.
3.       Calling methods and properties inside loops is expensive.
4.       Evaluating count etc. before loop starts. For example:

for(int i=0;i<Grid.Rows.Count;i++) {}can be written as
int iCount= Grid.Rows.Count; for(int i=0;i< iCount;i++){}

5.       Never write exception handling code inside loop. Keep the exceptions handling code outside of the loop for better performance.

32. Dispose Instead of Finalize

Avoid using Finalize unless it is absolutely necessary. It is normally better to dispose of unmanaged resources if no longer required.

33. Minimize Thread Creation

Avoid creating threads on a per-request basis. Also avoid using Thread.Abort or Thread.Suspend.

34. Leave Connection pooling Enable

Connection Pooling is enabled by default. It boosts application performance as existing connections can be re-used from the pool rather than created . Leave this option enabled.

35. Using Blocks

Using blocks can be used as a short form of try..finally and it should be used only for those objects that implement the iDisposable interface. Here is a code snippet.

Using(SqlConnection con=new SqlConnection(connectionString)
{
try
{
con.Open();

//some code
}
catch(Exception e)
{

}

}

In the above example,there is no need to dispose of the connection object. The Connection object will be disposed automatically when it is out of scope.
Continues…

When we are looking to optimize the performance of  web applications we should keep in mind about Memory Load, Processor Load and Network Bandwidth. Here are 50  best practices to improve the performance and scalability of ASP.NET applications.

1. Page.IsPostBack Property

Keep code which only needs to be loaded once inside an IsPostBack block.

if(!IsPostBack)
{
BindDropDownList();
LoadDynamicControls();
}

As a result there will be no unnecessary database hits and server processing.

2. Enable Buffering

A buffer is a region in main memory to store temporary data for input and output .Data retrival from memory is faster than data retrieval from disk. We should leave buffering on unless there is any specific reason to turn it off. By default buffering is enable.

3. Remove unused HttpModules

There may be lot of HttpModules in Machine.Config that are not actually required for a particular application. In this scenario we should remove those unused HttpModules from application specific web.config file.

4. Trim Page Sizes

Reduce page size by removing any unnecessary space and tab characters from the page. As a result network traffic will be reduced.

5. Use a CDN

Not a performance tip exclusive to ASP.NET but an important step in speeding up a site is to use a Content Delivery Network (CDN) . CDN’s minimize the latency site visitors experience when they request a larger file from a data center that is located geographically far away. CDN’s cache files at numerous edge locations around the world to minimize latency.
If you are using Azure consider using the Windows Azure CDN , Amazon’s CloudFront cheap and easy to integrate into a website (if you happen to have a WordPress blog you can  integrate S3 and CloudFront into WordPress)

6. Server.Transfer and Response.Redirect

“To perform client side redirection in ASP.NET, users can call Response.Redirect and pass the URL. When Response.Redirect is called, the server sends a command back to the browser telling it to request the page redirected to it.  An extra roundtrip happens, which hit the performance.  We can send information from the source page by using a query string.  There is a limitation on the length of a query string; it cannot be used to pass large amounts of data over the wire.

To perform server-side redirection, users can use Server.Transfer.  As the execution is transferred on the server, Server.Transfer does not require the client to request another page.  In Server.Transfer, by using HttpContext we can access the source page’s items collection in target page.  The drawback of using this method is that the browser does not know that a different page was returned to it.  It displays the first page’s URL in the browser’s address bar.  This can confuse the user and cause problems if the user tries to bookmark the page.  Transfer is not recommended since the operations typically flow through several different pages.”

7. Precompiling

Precompiling an ASP.NET Web site provides faster initial response time for users because pages do not have to be compiled the first time they are requested. This is particularly useful for large Web sites that are updated frequently. In order to achieve that we can use ASP.NET Compilation Tool (Aspnet_compiler.exe).

8. Session State Management

Efficient state management helps to boost the performance and scalability of application. It is not advisable to keep large objects in a session variable and it is optimal to make disable session state whenever it is not required. We can turn session state off either at the Page level or at the application level using the  config file.

9. ViewState

By default the viewstate is enabled for applications and we should disable it whenever it is not required. Otherwise it will increase the page size. Every byte added to a web page by enabling its viewstate causes two bytes of network traffic – one in each direction. Disable

view state in any of the following scenarios:

(i)  A readonly page where there is no user input.

(ii) A  page that does not postback to the server

(iii) A page which requires rebuilding server controls on each post back without checking the post back data.

It is best practice to turn ViewState off at the application level and then enable it as required at the page or even control level.

10. Caching

Probably the number one performance tip is to use caching. In order to store static data caching is ideal one. There are different types of caching: Page output caching, Page fragment caching data caching and we have to select the correct type as per requirement.
In almost all scenarios at least a part of a page can be cached.

11. Locking and Shared Resources

Acquire shared resources late and release them as early as possible.  Avoid locking unless absolutely necessary.  Do not set lock on the “this;” it is better to use a private object to lock on as follows:

public Class Test
{
private stativ readonly objLock=new Object();
public static Test Singleton
{
lock(ObjLock)
{
return new test();
}
}

Continues…