Barber, Scott. (2004). How Fast Does a Website Need to Be?
This article mainly addresses the web industry standard response time for a web page. At google, there are also a lot of researches regarding web site speed matters in order to understand and improve the search experience. Here I would like to share my reading about this topic as I realize the important of website response time in web development and web design. Web design adopted by usability, while usability is proven to impact Website performance. This report is actually based on Scott article, Web Development book and some references from google search on studies.
Acceptable Websites Performance:
User Sastifaction Response Time
I agree: websites performance “depends on” user personal feeling about whether a particular web page is responsive enough to be considered “acceptable”. As this article addresses that 1.5 seconds as a short interval for many situations, some audiences require a quick response:
8-second rule
• It all started with the 8-second rule. Usability studies have shown that 8.6 seconds is the maximum time
web users will wait for a page to download.
• Research of human factors has shown that “users will wait at most 8 to 10 seconds for a Web page to
display.
• Zona Research (2001) released a study which stated that users will stick around for up to eight seconds
waiting for a page to download.
5 seconds
• Then, a November 2008 report by Aberdeen suggests that business performance begins to decrease
after a response time delay of 5.1 seconds.
• A web site also states that the top 100 or retail sites online had pages that loaded up in under 5 seconds.
4 seconds
• NetForecast’s APDEX uses 4.0 seconds as the dividing line as to where users become frustrated.
• A JupiterResearch survey found that 33% of broadband shoppers are unwilling to wait more than four
seconds for a web page to load (Akamai 2006).
2 seconds
• The trend people expect that pages to load fast (2 seconds max, per sept 2009).
• And the most recent study, conducted by Forrester Consulting, also suggests that two seconds is the new
threshold in terms of an average online shopper’s expectation for a Web page to load, while 40
percent of shoppers will wait no more than three seconds before abandoning a retail or travel site.
I do agree that the user experience is more important to online success, AND that this number has decreased vastly, or rather, that user expectations for what represents an acceptable page response time has increased.
I strongly believe that this response time number represents user experience impacted negatively. As user sastifaction is inversely related to response time, response time “could be the single most important variable when it comes to user sastifaction”.
Google search results pages load: ~0.5 seconds
I also strongly believe that Google has greatly contributed to the high expectations towards web page load time. The Google search results pages load very fast (~0.5 seconds) and because people use Google daily and often.
Yahoo: 6 seconds
I ran across a web site states that Yahoo page load times of 6 seconds. The user switch to Google was based on an even quicker load than Yahoo! So do my experience!
Acceptable Benchmarks for Websites
As this article’s suggests a reasonable benchmarks that are acceptable for Websites at the moment, we need to analyze a website in terms of:
• Target user,
• What their needs,
• Where they are located,
• What their equipment and connection speed might be, etc.
Web usability principles
From my google search, I found that acceptable Web site performance is more related to website usability which is focus more on the basic usability principles in Web environment. These web design principles include:
(1) navigation
(2) response time
(3) credibility
(4) content.
This suggests:
• easy-to-use navigation
• frequent updating
• minimal download times
• relevance to users, and
• high-quality content that also takes advantage of capabilities unique to the online medium (Nielsen 1993)
Shackel's Acceptability Paradigm model
Shackel’s acceptability paradigm model illustrates four things (usability, likability, utility and speed) and the balance between those aspects and the user’s financial and social costs. When users make a decision about using a web site, they weigh:
· how useful it will be (usability)
· its perceived ease of use (utility)
· its suitability to the task (likability) which relatively affected
· speed (response time) of web page, and
· how much it will cost them (Cost)
Web Ussability Model
In this model, usability can be divided into four dimensions which ultimate success of any site: Availability,Responsivenes,Clarity, and Utilit. To satisfy customers, a Web site must fulfill these four distinct needs:
- Availability: A site that's unreachable, for any reason, is useless.
- Responsiveness: Having reached the site, pages that download slowly are likely to drive customers to try an alternate site.
- Clarity: If the site is sufficiently responsive to keep the customer's attention, other design qualities come into play. It must be simple and natural to use – easy to learn, predictable, and consistent.
- Utility: Last comes utility -- does the site actually deliver the information or service the customer was looking for in the first place?
Factors Affecting Web Response Time
Web response time—is affected by multiple and interacting factors as following:
User Psychology
User psychology is regarding personal tolerance levels. For a low tolorence person, poor performance at between 5 and 8 seconds, and slow at about 15 seconds will drive the users to abandon a site or get frustrated.
To explain for you in detail, when users requested a page, if there’s a notice appeares in the screen that said, "The information you have requested is being processed. This may take several minutes depending on the information you have provided. Please be patient." This may lead therm to wait a minute for some pages without noticing that it was slow.
For activity type, it takes time to download an MP3 or MPEG video. The users are likely to become frustrated before they realize that the performance is actually acceptable for the activity. In my experience, if I know what to expect, I am likely to be more tolerant of response times I might otherwise think of as slow.
System Considerations
System considerations include the following:
· system hardware
· network and/or Internet bandwidth of the system
· geographical replication
· software architecture
Users decisions are often based on the cost to achieve performance.
Usage Considerations
Usage considerations referring to the Web application. For example:
· An application that’s used by employees to enter large volumes of data needs to
be faster than a Web shopping site. For example, Amazon.com which has dynamic content and numerous images weighs in at a hefty 5 seconds on average. The popular online auction house, eBay.com, can take even longer to load.
· As for e-commerce websites have more images and use a database back-end will take longer to render a web page.
· A news site can be slow, as long as the text appears before the graphics.
· Interactive sites need to be faster than mostly static sites.
· Sites that people use for work-related activities need to be faster than sites that are used primarily for recreational purposes.
· The most popular websites on the web today do load quickly. For example, yahoo.com and google.com which contain simple text and a few small images load on average in 1 second which is admirable.
User Expectations
This article states that most users have the following expectations for normal page loads when surfing on high-speed connections:
· no delay or fast – under 3 seconds
· typical – 3 to 5 seconds
· slow – 5 to 8 seconds
· frustrating – 8 to 15 seconds
· unacceptable – more than 15 seconds
Resource Limitation
Limitations on resources such as time, money, people, hardware, networks, and software affect our performance requirements.
Stateholder Expectation
Stateholder generally want systems to be fast and scalable. This system needs to support ten times the current user base, it needs to be up 100% of the time and recover 100% of the data in case of down time, and it must be easy to use, make money.
Actually, Web-based systems don’t perform that fast in general. Client/server system are happy with a 3-second response time from a Web-based application. When stakeholders realize that users are satisfied with a "3-second application," they’re willing to change the requirement to "under 3 seconds."
Optimizing Web Pages
Using Server Side Cache
It is important for a websites user to consider server side caching. The .NET includes built-in caching to conserve server resources and offers a standard ASP websites. Also recommended is Port 80 Softwares httpZip which can handle web pages, no matter it is ASP, ASP.NET, php, or vanilla HTML.
Graphic Formats
Web designs rely on the use of graphic elements for its organization, navigation, and content. Web design work includes the use of animation, multimedia, audio, video, and interactive graphics for navigation menus and forms. Three of the most common types of file format used in Web sites are the Graphic Interchange Format (.GIF), the Joint Photographic Experts Group format (.JPG), and the Portable Network Graphic format (.PNG). Each type has good file compression capabilities as they typically have smaller file sizes compared to other formats. Smaller file sizes mean shorter user download times on the Web. Commonly used format that tend to have less compression include Windows Bitmap (.BMP), Encapsulated PostScript (.EPS), and Tagged Image File Format (.TIF).
Color depth, Transparency, Animation, and Interlacing
· Color depths affect both the quality and file size of the image. If the number of colors become higher, the image size becomes greater. Also, storing images in either indexed or RGB color affect the file size. Indexed color is mapped to the smaller color palette. The GIF format is an indexed color format. There is a common and optimized “Web-safe” color pallete. RGB formats known as true-color use 8 bits for each Red, Green and Blue value to form a 24-bit pixel palette display up to 16.7 million colors and produce images of photographic quality. However, not all graphics require this level of color depth, such as clipart or images that use fewer than 256 unique colors.
· Transparency assigns a single color in a graphic to be transparent, which allows graphics to blend with different backgrounds. PNG files allow semi transparency that allows control over how well it blends into te background on which it is placed.
· Animation allows multiple images to be combined into a short movie. Some types of animations don’t require special software plug-ins or program to view them, such as animated .GIF files, while others may require a specific program, especially if they are longer and more complex.
· Interlacing allows users to see pieces of the graphic on the screen as they load, while noninterlaced graphics remain unseen until the entire image is downloaded.
Resolution
Web pages are viewed on computer monitors, which typically display data at 72 ppi (pixels per inch). Therefore, saving files at a resolution of 72 ppi is a good way to minimize the file. If we are using graphics files, which were originally created for print media, they are typically saved at a high resolution (300 ppi).
Plug-ins Installer
Graphic formats are unique to different graphic design software and programs, such as animations, three-dimensional (3D) modeling, drafting files, video clips. Most require specific software programs or plug-ins to view. If the site uses these types of files, we should instruct users on how to properly download and view them. Provide file formats that will not require them to purchase additional software or spend a lot of time downloading appropriate viewers. We should consider the site’s target users when making the choice.
Conclusion
There’s no industry standard for Web performance. In the absence of a standard we must depend on our own consideration to determine how fast is fast enough for our application. We should consider web usability and accessibility that are vital aspects of the Web development process.
Reference
5, 10, 15 seconds? How Long Will You Wait For a Web Page to Load? Retrieved on
Baehr, C. M. (2007). Web Development: A Visual-Spatial Approach. New Jersey: Pearson
Prentice Hall.
Speed Matters. Tuesday, June 23, 2009 at 6/23/2009 03:15:00 PM. Retrieved on 23 July 2010.
http://googleresearch.blogspot.com/2009/06/speed-matters.html
Hodgson, Tim. Website speed: How fast should your website be? Retrieved on 23 July 2010.
http://www.websitegoodies.com/website-development/website-speed-how-fast-should-your-website-be
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