If your WordPress or Magento website is slow to load, you will lose a lot of visitors because of this. Most web surfers are impatient, and are not going to give you long to impress them before they hit the back button and go to the next site in the search results. If you want to impress your visitors, you must optimize your site to load as quickly as possible. Here are a few tips:
Optimize your images for your site. Use the best compression you can without sacrificing quality. Create small thumbnails for images shown in-page, and allow the user to click those thumbnails to view uncompressed, full size images in a lightbox if they so desire.
Turn on Compression
Use mod_deflate module to compress HTML, XML and CSS. In many cases you can reduce HTML content to just 1/5th of its original file size by enabling compression on your server. The performance overhead is minimal, and in a world where bandwidth is the main bottleneck it makes sense to use CPU power to reduce bandwidth consumption.
Serve Different Pages for Different Devices
Take advantage of browser and platform detection capabilities to serve different pages for mobile, desktop and tablet devices. Serve super-high resolution images to iOS devices with retina displays, and offer lower resolution images for smaller mobile devices. If possible, also use different layouts for touch screens vs keyboard+mouse interfaces.