Lead Poisoning is Preventable. If your home was built before 1978, old lead paint on your walls, doors, windows, and sills may be dangerous. We are the Keepers of the Cog. In so being, we also maintain the sacred text wherein lie the simple truths of cycling etiquette known as The Rules. Best Practices for Speeding Up Your Web Site. The Exceptional Performance team has identified a number of best practices for making web pages fast. Most of this time is tied up in downloading all the components in the page: images, stylesheets, scripts, Flash, etc. Reducing the number of components in turn reduces the number of HTTP requests required to render the page. This is the key to faster pages. One way to reduce the number of components in the page is to simplify the page's design. Best Practices for Speeding Up Your Web Site. The Exceptional Performance team has identified a number of best practices for making web pages fast. The FAFSA is now available! Get the facts from College Goal Georgia and fill it out! But is there a way to build pages with richer content while also achieving fast response times? Here are some techniques for reducing the number of HTTP requests, while still supporting rich page designs. Combined files are a way to reduce the number of HTTP requests by combining all scripts into a single script, and similarly combining all CSS into a single stylesheet. Combining files is more challenging when the scripts and stylesheets vary from page to page, but making this part of your release process improves response times. CSS Sprites are the preferred method for reducing the number of image requests. Combine your background images into a single image and use the CSS background- image and background- position properties to display the desired image segment. Image maps combine multiple images into a single image. The overall size is about the same, but reducing the number of HTTP requests speeds up the page. Image maps only work if the images are contiguous in the page, such as a navigation bar. Defining the coordinates of image maps can be tedious and error prone. Using image maps for navigation is not accessible too, so it's not recommended. Law School Admission Council helps prospective law students with easing the law school admission process. Find out more about becoming an attorney. CSUMentor is a website designed to help students and their families learn about the California State University (CSU) system. USGA Membership makes the perfect gift. Each membership level comes with its own benefits and opportunities, so simply choose the one that fits the golfer in your life. 2016 Ninth Circuit Judicial Conference Videos Now Available Videos of general sessions from conference now online. Our mission is to promote student achievement and preparation for global competitiveness by fostering educational excellence and ensuring equal access. I am happy to release my new book: The Inevitable. It is about the deep trends in the next 20 years that will shape your life. I suggest we embrace these changes. Inline images use the data: URL scheme to embed the image data in the actual page. This can increase the size of your HTML document. Combining inline images into your (cached) stylesheets is a way to reduce HTTP requests and avoid increasing the size of your pages. Inline images are not yet supported across all major browsers. Reducing the number of HTTP requests in your page is the place to start. This is the most important guideline for improving performance for first time visitors. As described in Tenni Theurer's blog post Browser Cache Usage - Exposed!, 4. Making your page fast for these first time visitors is key to a better user experience. Deploying your content across multiple, geographically dispersed servers will make your pages load faster from the user's perspective. But where should you start? As a first step to implementing geographically dispersed content, don't attempt to redesign your web application to work in a distributed architecture. Depending on the application, changing the architecture could include daunting tasks such as synchronizing session state and replicating database transactions across server locations. Attempts to reduce the distance between users and your content could be delayed by, or never pass, this application architecture step. Remember that 8. 0- 9. Flash, etc. This is the Performance Golden Rule. Rather than starting with the difficult task of redesigning your application architecture, it's better to first disperse your static content. This not only achieves a bigger reduction in response times, but it's easier thanks to content delivery networks. A content delivery network (CDN) is a collection of web servers distributed across multiple locations to deliver content more efficiently to users. The server selected for delivering content to a specific user is typically based on a measure of network proximity. For example, the server with the fewest network hops or the server with the quickest response time is chosen. Some large Internet companies own their own CDN, but it's cost- effective to use a CDN service provider, such as Akamai Technologies, Edge. Cast, or level. 3. For start- up companies and private web sites, the cost of a CDN service can be prohibitive, but as your target audience grows larger and becomes more global, a CDN is necessary to achieve fast response times. At Yahoo!, properties that moved static content off their application web servers to a CDN (both 3rd party as mentioned above as well as Yahoo. Switching to a CDN is a relatively easy code change that will dramatically improve the speed of your web site. A first- time visitor to your page may have to make several HTTP requests, but by using the Expires header you make those components cacheable. This avoids unnecessary HTTP requests on subsequent page views. Expires headers are most often used with images, but they should be used on all components including scripts, stylesheets, and Flash components. Browsers (and proxies) use a cache to reduce the number and size of HTTP requests, making web pages load faster. A web server uses the Expires header in the HTTP response to tell the client how long a component can be cached. This is a far future Expires header, telling the browser that this response won't be stale until April 1. This example of the Expires. Default directive sets the Expires date 1. It has no effect on the number of HTTP requests when a user visits your site for the first time and the browser's cache is empty. Therefore the impact of this performance improvement depends on how often users hit your pages with a primed cache. By using a far future Expires header, you increase the number of components that are cached by the browser and re- used on subsequent page views without sending a single byte over the user's Internet connection. It's true that the end- user's bandwidth speed, Internet service provider, proximity to peering exchange points, etc. But there are other variables that affect response times. Compression reduces response times by reducing the size of the HTTP response. Starting with HTTP/1. Accept- Encoding header in the HTTP request. The web server notifies the web client of this via the Content- Encoding header in the response. It was developed by the GNU project and standardized by RFC 1. The only other compression format you're likely to see is deflate, but it's less effective and less popular. Gzipping generally reduces the response size by about 7. Approximately 9. 0% of today's Internet traffic travels through browsers that claim to support gzip. If you use Apache, the module configuring gzip depends on your version: Apache 1. There are known issues with browsers and proxies that may cause a mismatch in what the browser expects and what it receives with regard to compressed content. Fortunately, these edge cases are dwindling as the use of older browsers drops off. The Apache modules help out by adding appropriate Vary response headers automatically. Servers choose what to gzip based on file type, but are typically too limited in what they decide to compress. Most web sites gzip their HTML documents. It's also worthwhile to gzip your scripts and stylesheets, but many web sites miss this opportunity. In fact, it's worthwhile to compress any text response including XML and JSON. Image and PDF files should not be gzipped because they are already compressed. Trying to gzip them not only wastes CPU but can potentially increase file sizes. Gzipping as many file types as possible is an easy way to reduce page weight and accelerate the user experience. This is because putting stylesheets in the HEAD allows the page to render progressively. Front- end engineers that care about performance want a page to load progressively; that is, we want the browser to display whatever content it has as soon as possible. This is especially important for pages with a lot of content and for users on slower Internet connections. The importance of giving users visual feedback, such as progress indicators, has been well researched and documented. In our case the HTML page is the progress indicator! When the browser loads the page progressively the header, the navigation bar, the logo at the top, etc. This improves the overall user experience. The problem with putting stylesheets near the bottom of the document is that it prohibits progressive rendering in many browsers, including Internet Explorer. These browsers block rendering to avoid having to redraw elements of the page if their styles change. The user is stuck viewing a blank white page. The optimal solution is to follow the HTML specification and load your stylesheets in the document HEAD. The HTTP/1. 1 specification suggests that browsers download no more than two components in parallel per hostname. If you serve your images from multiple hostnames, you can get more than two downloads to occur in parallel. While a script is downloading, however, the browser won't start any other downloads, even on different hostnames. In some situations it's not easy to move scripts to the bottom. If, for example, the script uses document. There might also be scoping issues. In many cases, there are ways to workaround these situations. An alternative suggestion that often comes up is to use deferred scripts. The DEFER attribute indicates that the script does not contain document. Unfortunately, Firefox doesn't support the DEFER attribute. In Internet Explorer, the script may be deferred, but not as much as desired. If a script can be deferred, it can also be moved to the bottom of the page. That will make your web pages load faster. They were supported in Internet Explorer starting with version 5, but were deprecated starting with IE8. As an example, the background color could be set to alternate every hour using CSS expressions: background- color: expression( (new Date()). Hours()%2 ? The CSS property is set to the result of evaluating the Java. Script expression. The expression method is ignored by other browsers, so it is useful for setting properties in Internet Explorer needed to create a consistent experience across browsers. The problem with expressions is that they are evaluated more frequently than most people expect. Not only are they evaluated when the page is rendered and resized, but also when the page is scrolled and even when the user moves the mouse over the page.
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