In my previous post, I mentioned the disappointing performance of Dreamweaver CS5 while editing a site very similar in appearance to this blog page.
I like the aurora borealis look to the background and that you can still see that borealis behind the grey framing that holds the content of my blog. This effect is achieved by a single-pixel PNG graphic. As most web developers can tell you, it is possible to "stretch" a graphic to any given size. So this single-pixel grey image takes advantage of the transparency features of PNG and is stretched to make up the grey framing.
The framing itself is three <div> tags and the same PNG image is used as a background for each of them. When it is "layered" over itself twice, as in the postings content and right-side menus, it becomes a darker grey. But it still lets that borealis image appear through without obscuring the text.
I could not type text into the web site due to the performance issues with Dreamweaver. It took several dozen seconds for my words to render in the Design View. Interestingly, the Code View did not have any issues at all. That was an important clue.
I collected a Performance Monitor trace and capturing the Process and Processor objects while Dreamweaver was running. I noticed that as soon as I switched to the Design View of Dreamweaver after editing my Cascading Style Sheet to use the PNG image that the "% Privileged Time" for the Dreamweaver process spiked up to about 90% and held steady there for quite some time. You can see that spike in the picture to the left.
The "% Privileged Time" is also known as kernel mode time. Without getting too sidetracked, a Windows process has "user mode time" and "kernel mode time." User mode is the code written by the developers and kernel mode is calls made into Windows. So, to render my web site in Design Mode, Dreamweaver was making extensive calls into the Windows API.
This was not a problem with Dreamweaver CS3. So somewhere in the two versions since then, Adobe changed what they were doing within the Design Mode code. It was time to open a support case with Adobe…