Tips to speed up website


"Experiments demonstrate that increasing web search latency 100 to 400ms reduces the daily number of searches per user by 0.2% to 0.6%. Furthermore, users do fewer searches the longer they are exposed. For longer delays, the loss of searches persists for a time even after latency returns to previous levels." Google says.

I will list a variety of factors (+ useful tips from Yahoo and Google) and will use SEOmoz as my example:

Note: Making a backup before starting is necessary!

a) Server

Choosing suitable hosting for your venture is the first step in starting a website. Hosting with a professional configuration can be of big help. Here you can find some good tips about choosing hosting.

1. Leverage browser caching

"Expires headers tell the browser whether a resource on a website needs to be requested from the source or if it can be fetched from the browser’s cache. When you set an expires header for a resource, such as all jpeg images, the browser will store those resources in its cache. The next time the visitor comes back to the page it will load faster, as the browser will already have those images available," says CJ Patrick in a nice article about how to use expire headers to set caching: Expires Headers for SEO

Unfortunately, it seems that SEOmoz doesn't use expiration for stylesheets and images.

2. Enable Keep-Alive

"A Keep-Alive signal is often sent at predefined intervals and plays an important role on the Internet. After a signal is sent, if no reply is received, the link is assumed to be down and future data will be routed via another path until the link is up again," says wikipedia.

In fact, HTTP Keep-Alive allows TCP connections to stay alive and it helps reducing the latency for subsequent requests. So contact your hosting provider and tell them to think twice about this! Most hosting companies disable this feature, (including SEOmoz's host) because it's an optional feature (whenever it transfers less than 60 bytes per request).

3. Enable gzip compression

Compressed HTTP respond

* Image by


Gzipping reduces the size of the HTTP response and helps to reduce response time. It's an easy way to reduce page weight. You can enable it by adding the following code to your .htaccess file:

# compress text, html, javascript, css, xml:
AddOutputFilterByType DEFLATE text/plain
AddOutputFilterByType DEFLATE text/html
AddOutputFilterByType DEFLATE text/xml
AddOutputFilterByType DEFLATE text/css
AddOutputFilterByType DEFLATE application/xml
AddOutputFilterByType DEFLATE application/xhtml+xml
AddOutputFilterByType DEFLATE application/rss+xml
AddOutputFilterByType DEFLATE application/javascript
AddOutputFilterByType DEFLATE application/x-javascript
# Or, compress certain file types by extension:
<files *.html>
SetOutputFilter DEFLATE




SEOmoz uses gzip. However, some external javascripts (AdRoll, Simpli and CloudFront) could reduce transfer size more than 60% by using gzip.

4. Make landing page redirects cacheable

Mobile pages redirect users to a different URL, (for example to so making a cacheable redirect can speed up page load time for the next time visitors try to load site. Use a 302 redirect with a cache lifetime of one day. It should include a Vary: User-Agent as well as a Cache-Control: private. This way, only those visitors from mobile devices will redirect.

Since SEOmoz doesn't support any specific mobile version, it can't have this problem (someone should take care of the bad behavior of SEOmoz's website on mobile devices)!

5. Use a CDN

how CDN works

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. As you can see in the above image, it loads from different servers, based on the visitor's region. You can compare CDN hosting with standard web hosting here.

It seems that SEOmoz uses Amazon CloudFront for this functionality and I've tried MAXCDN, It's awesome, too. You can manage your caches and lots of other useful tools in one WordPress using W3 Total Cache.

b) Content elements

Since you don't have total access to your server, content elements are the most important things that you can manipulate. Let's start with the most obvious weakness of SEOmoz:

1. Minimize redirects

Sometimes to indicate the new location of a URL, track clicks, connect different parts of a site together or reserve multiple domains, you need to redirect the browser from one URL to another. Redirects trigger an extra HTTP request and add latency. Only keep redirects which are technically necessary and you can't find any other solution for it. These are Google's recommendations:


This image shows what happens when your browser tries to load

SEOmoz redirects problem

As you can see, the greatest latency is the result of some external redirect chains. SEOmoz is using about 20 redirect chains that slow down the load time about 3000 milliseconds.

2. Remove query strings from static resources

You can't cache a link with a "?" in its URL even if a Cache-control: public header is present. The question mark acts the same as Ctrl+F5. Use query strings for dynamic resources only. SEOmoz is using two dynamic URLs with "?" because of using KISSmetrics, but 2-3 queries are reasonable ;)

3. Specify a character set

Specify a character set in HTTP headers to speed up browser rendering. This is done by adding a simple piece of code into your header:


Note: Some CMSs use functions for character set (like WordPress with <?php bloginfo('charset'); ?> ). I suggest that if you are sure about your character set, write it instead of using PHP functions. It helps to minimize request size, so try to use HTML instead of PHP everywhere that is possible.

4. Minify your codes

Minify your codes

Removing HTML comments, CDATA sections, whitespaces and empty elements will decrease your page size, reduce network latency and speed up load time.

You can use simple online tools like Will Peavy minifier, and if you are using WordPress, Autoptimize can optimize and compress your codes and it supports CDN as well. By the way, SEOmoz could save 620B by compressing its HTML.

5. Avoid bad requests

Difference between optimized page and bad request page

Broken links result in 404/410 errors. These cause wasteful requests. Fix your broken URLs (pay special attention to images). Use online broken link checker or use WordPress link checker for free. You can also read about Xenu Link Sleuth and Screaming Frog tools at SEOmoz that can be really helpful.

6.Serve resources from a consistent URL

It's best to share Google's recommendation:

"For resources that are shared across multiple pages, make sure that each reference to the same resource uses an identical URL. If a resource is shared by multiple pages/sites that link to each other, but are hosted on different domains or hostnames, it's better to serve the file from a single hostname than to re-serve it from the hostname of each parent document. In this case, the caching benefits may outweigh the DNS lookup overhead. For example, if both and use the same JS file, and links to (which will require a DNS lookup anyway), it makes sense to just serve the JS file from In this way, the file is likely to already be in the browser cache when the user goes to"

7. Reduce DNS lookups

Reduce DNS lookups

DNS lookups take a meaningful amount of time to look up the IP address for a hostname. The browser cannot do anything until the lookup is complete. Reducing the number of unique hostnames may increase response times. Just look at how a DNS lookup can take about 3 seconds of load time in SEOmoz. You can measure yours, by using Pingdom Tools. I do want to mention that when I re-tested the homepage of from a server in Dallas, it showed better results than it did before I started writing this article.

Note: Sprite your images. This means put images that are loading every page of your site together to reduce your DNS lookups. SEOmoz combined lots of its images into one, like this sprite image. You can find more information on SpriteMe

c) CSS, JS and Images

1. Specify image dimensions

Your browser begins to render a page before images are loaded. Specifying image dimensions helps it to wrap around non-replaceable elements. If no dimensions are specified, your browser will reflow once the images are downloaded. In order to do that in <img> elements, use height and width tags specifications.

Note: Don't use dimensions to scale images on the fly -- the user will still be downloading the original file size, even if the image doesn't take up as much space on the screen.

2. Optimize images

comments in image file

Images can contain extra comments and use useless colors. Keeping image sizes to a minimum is a big help for users on slow connections. Try to save in JPEG format. You can use a CTRL+SHIFT+ALT+S shortcut to save an optimized image in Adobe Photoshop, use Yahoo!, or if you are using WordPress, you can install the WP plugin.

SEOmoz could save more than 50KB by optimizing images on the main page, particularly those in the slider.

3. Put CSS at the top and JS at the bottom

Putting stylelsheets in the document head of the page prohibits progressive rendering, so browsers will block rendering to avoid having to redraw elements of the page. In most of cases, users will face a white page until the page is loaded completely. This also helps you to make a standard web page according to W3 standards. And, put your javascript code at the bottom of the page for the same reason.

There are of other ways to speed up a web page, but I have tried to write about the most important ones which even professional bloggers (like SEOmoz) can sometimes overlook. Of course, site speed is not the main goal but even an ideal website with a bad load time will find it hard to achieve success. Run the fastest website you can in order to reach your goals faster.

Now, let me repeat: DO NOT forget to make a backup before making any changes and don't forget to share your tips or questions by commenting. :)