Get a good hosting You may not think that this is important, but if you want your site to display really fast you need to get a good hosting. This is the first step in having a fast site, which also translates into more views, which also translates into a better SEO, which finally translates into more sales. (affiliate links below) There are three hosting companies which i recommend:
Media Temple: http://mediatemple.net - if you want a premium WordPress hosting which is easy to manage and works pretty well, this is a good choice to host your website on.
A Small Orange: http://asmallorange.com - this is another good hosting company, which i’m currently using to host my theme demos on. If you bought this theme you probably liked the speed as well, so i highly recommend ASO to host your themes on (especially the Cloud VPS option).
WPEngine: http://wpengine.com - definitely not as cheap as the two examples above, but if you really want an incredibly fast website and absolutely no headaches in managing it, WPEngine is the way to go. With it you don’t have to worry about security, caching, updates, etc. Everything is handled by a great theme of professionals ready to help you with everything. You just need to care about your content.
Always optimize/compress your jpeg images before uploading them to the server. Large images should be compressed at around 90% image quality and you should also try to limit the use of lossless image files (uncompressed pngs).
I can’t recommend enough the necessitiy go good caching. If you use a managed hosting such as WPEngine you don’t need this. But if you are using ASO or MT or any other hosting you need to cache your content. For this purpose, i recommend W3 Total Cache! It’s a great and easy to use plugin, and with only a bit of work you can double your site’s speed. See this ticket for more info on how to configure this plugin: