Download speed is probably the biggest complaint among internet users. Along with ads, speed makes up for 60% of the total complaints. This is precisely why creating websites optimized for speed is an essential part of web design.

There are a couple of root causes behind very slow web pages. For one, the site could be hosted by a slow server (bad hosting). These include slow computer performance, slow internet service providers and bad internet connection. The one thing you can control as a web designer is "page weight", or the size of a web page. The following items add to page weight:

Non-optimized images

Web and graphic designers often struggle between the quality of an image placed on a web page and its size – because there's almost always an inverse relationship between the two. There are many ways in which web designers can optimize images for web use.

Web Design Tip: Set the image resolution of your images to 72 dots per inch (dpi). Slicing large images into smaller ones also helps, as well as using the right image type.

Improper use of tables

A lot of web designers make this mistake – using tables for laying out elements of a web page. Tables are meant for displaying the relationship among sets of data. Web designers shouldn't use it as an excuse not to learn how to use HTML container elements with CSS.

Since tables load fast, a common misconception among web designers is that by using tables for layout, you can ensure fast download speeds. This is absolutely not true. To lay out website elements, you would have to use nested tables. Nested tables load very slowly since browsers would have to search for the closing tags for the main table and for each of its nested elements before starting to display them on screen.

Web Design Tip: Use tables as they were intended – for handling tabular data, not for layout. Learn how to use CSS-formatted DIV and SPAN containers instead.

Unnecessary Flash elements

Flash is undoubtedly flexible, since it works on all platforms and designers can enjoy freedom in terms of creativity. Using too much flash for your site is impractical, however, for two major reasons. First off, Google and search engines cannot "see" Flash elements and therefore cannot index them. Second, it takes a long time for them to load, especially if you have a lot of layers and images inside the Flash document. They may look great but staring at preloaders too long will only put off your visitors and make them want to leave faster than you can say "full flash".

Web Design Tip: Learn how to optimize Flash elements and use them sparingly. If it can be replaced by animated GIFs, then use the latter instead.

Large background images

Instead of using a large splash image for the backdrop of your site, try to use a small image tiled across the screen. Not only will this keep your customers attention on what's most important – your content – you can rest assured that your website is loading fast. This applies to headers and footers as well.

Web Design Tip: Instead of using a large header whose dimensions are 800 by 260 pixels, crop or use only a small part of it while setting a background fill for the header to match the background of your image. This should cut down on your header's file size.

Too many HTTP requests in one page

The more components – style sheet files, images, scripts, objects –you have on a web page the more HTTP requests it makes. Remember that 40% to 60% of your website's visitors come with an empty cache – more HTTP requests mean astoundingly low load speeds for them.

Web Design Tip: Go with simplicity and minimalism. Divert most of your effort to creating rich content for your website instead of turning it into eye candy. Combine files if you can. For instance, instead of using 3 to 4 separate stylesheets, merge them to reduce the count to 1 or 2.

Creating fast-loading websites is essential in good web design. Just avoid the common reasons I mentioned above and you'll reap the benefits of loyal visitors in no time. After all, having slow loading web pages on your site could cost you more than your customer's time. It just might cost you your Google ranking.