+ Start a Discussion

How to make sure that a VF page's performance is efficient

Hi All,
How to analyze or measure the performance of a visualforce page, to make sure that its performance is efficient enough, i mean what are the principles to be followed, for instance, in terms of page loading time while diaplaying records or performing DML operations on huge amount of data on a particular visualforce page.i have seen lot of references aout best practices of VF page but but could not find much info about my above question.

deepak balur 19deepak balur 19
Read the VF developer guide; Best practices section at the end of the guide. 
nagendra 6989nagendra 6989

Visualforce was designed to provide developers with the ability to match the functionality, behavior, and performance of standard Salesforce pages. If your users experience delays, unexpected behavior, or other issues specifically around Visualforce, there are several actions you can take to not only improve their experience, but to also make for improved coding.

Following are some of the top best practices in order to improve the performance of the visual force page 

a)Do not hardcode picklists in Visualforce pages; include them in the controller instead.
b)Javascript and CSS should be included as Static Resources allowing the browser to cache them.
c)Reference CSS at the top and JavaScript a the bottom of Visualforce pages as this provides for faster page loads.
d)Mark controller variables as "transient" if they are not needed between server calls. This will make your page load faster as it reduces the size      of the View State.
e)Use <apex:repeat> to iterate over large collections.
f)Use the cache attribute with the <apex:page> component to take advantage CDN caching when appropriate
g)Use standard objects and declarative features.
h) Limit the amount of data that your Visualforce pages display.
i) Delay expensive calculations or data loading.
j) Offload processing to asynchronous tasks.
k) Cache global data in custom settings.
l) Write efficient: – Apex and SOQL – Getter methods
m)Optimize: – View state – Component hierarchies – Polling – HTML – CSS – JavaScript – Image usage – Pages for Internet Explorer

The following is a list of commonly encountered Visualforce performance issues and their possible solutions:

View State Size

The view state size of your Visualforce pages must be under 135 KB. By reducing your view state size, your pages can load quicker and stall less often.
You can monitor view state performance through the View State tab in the development mode footer and take the following actions:
Use the transient keyword in your Apex controllers for variables that aren’t essential for maintaining state and aren’t necessary during page refreshes.
If you notice that a large percentage of your view state comes from objects used in controllers or controller extensions, consider refining your SOQL calls to return only data that's relevant to the Visualforce page.
If your view state is affected by a large component tree, try reducing the number of components your page depends on.

Load Times

Large page sizes directly affects load times. To improve Visualforce page load times:
Cache any data that is frequently accessed, such as icon graphics.
Avoid SOQL queries in your Apex controller getter methods.
Reduce the number of records displayed on a page by:
Limiting the data coming back from SOQL calls in your Apex controllers. For example, using AND statements in your WHERE clause, or removing null results
Taking advantage of pagination with a list controller to present fewer records per page
“Lazy load” Apex objects to reduce request times.
Consider moving any JavaScript outside of the <apex:includeScript> tag and placing it into a <script> tag right before your closing <apex:page> tag. The <apex:includeScript> tag places JavaScript right before the closing <head> element; thus, Visualforce attempts to load the JavaScript before any other content on the page. However, you should only move JavaScript to the bottom of the page if you’re certain it doesn’t have any adverse effects to your page. For example, JavaScript code snippets requiring document.write or event handlers should remain in the <head> element.

In all cases, Visualforce pages must be under 15 MB.

Multiple Concurrent Requests

Concurrent requests are long-running tasks that could block other pending tasks. To reduce these delays:
Action methods used by <apex:actionPoller> should be lightweight. It’s a best practice to avoid performing DML, external service calls, and other resource-intensive operations in action methods called by an <apex:actionPoller>. Carefully consider the effect of your action method being called repeatedly by an <apex:actionPoller> at the interval you specify, especially if it’s used on a page that will be widely distributed, or open continuously.
Increase the time interval for calling Apex from your Visualforce page. For example, when using the<apex:actionPoller> component, you could adjust the interval attribute to 30 seconds instead of 15.
Move non-essential logic to an asynchronous code block using Ajax.

Queries and Security

By using the with sharing keyword when creating your Apex controllers, you have the possibility of improving your SOQL queries by only viewing a data set for a single user.

Preventing Field Values from Dropping Off the Page

If your page contains many fields, including large text area fields, and has master-detail relationships with other entities, it may not display all data due to limits on the size of data returned to Visualforce pages and batch limits. The page displays this warning: “You requested too many fields to display. Consider removing some to prevent field values from being dropped from the display.”
To prevent field values from being dropped from the page, remove some fields to reduce the amount of data returned. Alternatively, you can write your own controller extensions to query child records to be displayed in the related lists.

If you can follow the above best practices and rectify the performance issues hope your visual force page's performance will improve drastically.

Please let me know if it helps you ........

Thanks & Regards