Web site optimization for speed
The speed of the web site has direct impact on both; search engines and human visitors.
Web page speed and search engines’ robots
Search engines are based on automated software agents that visit the web pages and collect information about their contents and links to other web pages. These software agents are called: spiders, crawlers, search engine robots and bots. They are part of the search engines and their ability to open and read the content of the web page is one of the most important factors for one web page to get in the search engine data base. The enormous number of web pages existing in Internet requires that the time spent by this search engine bots to be very short. Hence, if the web page does not satisfy this requirement, the robot will see only some part of its content. If the delay is too long, the web page might be dropped by the search engine and not indexed at all.
Web page speed and the human visitors
It is proven that when visiting a web site for first time the visitor will spend less than 30 seconds before decide whether to stay longer on that particular web site or to leave it. However, if it takes more than 5 seconds for one web page to show some if not the whole content, most likely the visitor will close it and move to the next web site in his/her list, which in most cases is the search engine result page SERP. To keep visitors on our web site, it is important to ensure that the time necessary for our web pages to load in the visitor’s browser window, is as short as possible. Remember, slow web pages can not be compensated with good web page content. No matter, how unique and how beautiful is the web page if it takes ages to show in the browser’s window.
In this article we shall not consider the quality of the Internet connection available at the visitor’s side, regardless that it also play a significant role in his/her experience, when browsing our web site. Instead, we will focus only on these factors that directly depends on the web site owner and web site designers.
Factors that affect the speed of the web site
- Technical factors – the quality of the hosting package: speed of the web hosting server machine, number of web sites hosted on the same machine, Internet connection bandwidth (speed) available to the hosting provider and to the customers in their hosting packages
- Software and design factors – quality of the web design and web programming. These are the factors that directly depend on the persons involved in the web design. Hence, in this article we will focus mostly on the basic design rules and recommendations.
Web site /web page/ optimization for speed
Web page graphics objects – pictures, images, photos, charts, etc. These are the most common objects that increase the web page total size and cause delay when it loads in the browser. The total size of one web page should be kept less than 50K that will guarantee the page can be loaded for less than 10 seconds using Internet with speed 56Kb/s. To achieve this recommendation consider the following basic rules:
- Keep the number of different pictures in one web page as less as possible
- Keep the picture size (in pixels) small, this will decrease the picture file size as well
- Keep the number of colors in the pictures small. This has direct impact on their file size.
- Reuse the images in the different web pages where it is possible, especially where the images are used for background formatting. Once the image file is downloaded to the visitors computer, it will be cached and its local copy reused afterwards for the next web pages opened from the same web site
The total size of all images in one web page should be less than 30K. This will left another 20K to be shared between the web page code elements and the web page content.
The web page code is not visible for the visitors. They see textual content and images only. Hence, to left more room for the actual web site content, it is important to optimize the web page code elements too.
Web page code elements
Most of the elements in one web page have their own attributes like size, color, background color, border, thickness, etc. All these object types and their attributes can be found in one web page many times. Is it necessary to repeat every time this text is bold and green, this table cell background is blue, etc? No, not at all if we use CSS for web page style formatting.
Use CSS to create different formatting styles that will be applied and reused afterwards in all web pages that belong to one and the same web site. This way directly cut the size of the HTML code several times and load all formatting styles only once – with the loading of the very first web page. Using the CSS as an external file will cause the file to be cached in the web browser and on the second page it will not be downloaded as the file will already exists in the visitor’s PC.
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