That's an interesting question.
Off-topic: Will it be Sencha on-line videos of this year's conference posted any time soon?
IE6 Memory Leak
So we looped 25 array grids (from the ext examples) in an absolute layout using various ext versions. So here's how we tested the timeings:
1. Opened a new IE6 window with "about:blank" in it.
2. Loaded our local file path of the html file with the grids and ext version (all static files, no HTTP)
3. Captured the time in ms to load
4. Reloaded the page and kept capturing the time
Here is where we noticed a major memory leak in 4.1.pr1:
Load 1 - 4312ms
Reload - 5437ms
Reload - 6922ms
Reload - 8407ms
Reload - 10188ms
Reload - 11109ms
Reload - 12828ms
Reload - 14469ms
Reload - 16047ms
Reload - 17110ms
In Mozilla and Chrome, it was consistant, but IE6 was leaking real bad. Ext 4.0.2a and 4.0.7 remained consistent at about 10000ms each for the same set of tests.
Ext 3.4 averaged 1683ms to build the same thing, which is embarssing for the ext 4.x series. So even at best, Ext 3 was about 3 times faster than the tuned ext 4.1-pr1.
As we've migrated several of our corporate apps from Ext 3 to Ext 4.x, performance has been a MAJOR concern for us, across the board. I've been with you guys since version 1 and hope you guys can sort this out as it is very damaging to the reputation of the framework and product.
NOTE - The column header lines (splits) were also not rendering...