As applications grow richer (and by extension, heavier), technologies like AJAX, Flash and Flex help maintain application performance, in this case speed, by enabling browsers to perform much of the application work.
The changing role of the browser
The browser is no longer a simple renderer. It’s actually doing work — running code on your behalf. It is also the first time all web application components come together — the browser has evolved from a rendering engine to an integration platform.
With HTML5, web apps will now be able to rival the performance of native and desktop applications by providing a full desktop like experience on a website to your end users. That’s where the bar is going to be set. You will no longer be able to distinguish between full native desktop applications and browser based ones given these capabilities. This is perhaps most apparent in mobile.
HTML5 will remake the Web and enable basic websites to do much more — from tracking our location to storing more of our data in the cloud. By using a variety of techniques and technologies, your sites and apps can feel more responsive and your users will get more done. Writing fast and responsive apps is not important for only your end user’s experience, it’s important for your bottom line.
Web performance is multi-dimensional. Leverage advanced browser capabilities as much as you can, but remember each browser in turn has different capabilities and its own performance characteristics.