I measured the time needed to create 200 Buttons in RAP 1.4 and RAP 1.5M3, and it shows a considerable performance boost (at least for the browsers i tested). One reason for this is that we changed from quirksmode to standard rendering in IE9, which among other things, finally allowes us to use its new HTML5-features (in this case SVG and CSS3). I expect another little boost with IE10, which has even more CSS3 support.
However, what i did not expect was a significant improvement in any other browser, in this case Google Chrome. This is likely due to the implementation of the JSON-based RAP-protocol. It remains to be seen how this develops, as work on the protocol is still going on. Currently eval() is used to parse the JSON. In the final release we will probably use other methods, such as the native JSON-parser present in many modern browser. Older browser may gain only little or no performance.
What is really awesome though is the improvment of the GC/SWT-Canvas performance in IE9 (and only IE9). Drawing in browser (without any plug-ins) used to be a real pain. While other browser adopted the HTML5-Canvas and SVG standard very early on, Microsoft stubbornly stuck to its horribly old VML implementation, making my work needlessly hard. One of the main problems with VML is that it gets exponentially slower the more elements you draw, from about 200 elements on it’s almost painful to watch. But this is 2011, HTML5 is all the buzz, and even MS could no longer ignore it. IE9 now has a decent HTML5-Canvas implementation that we use in RAP 1.5, and it shows:
The fine print: