Re: Measuring DOM performance

> Covers in the sense that it uses the method for some form of testing
> (the particulars will, naturally, need to be analyzed further). It
> sounds like you're more interested in comprehensive regression tests

I'm interested in several things, if I get to wish for ponies and rainbows:

1)  Performance regression tests.
2)  Tests that might indicate whether the DOM performance improvements
     we think we're making actually have any effect on something other
     than our tests.
3)  Tests that might indicate where we should prioritize our work in
     order to maximize impact on web content.

> whereas Dromaeo is more optimized towards analyzing the performance of
> the most-commonly performed tasks (crossed by most DOM methods).

I'm not entirely convinced.  Maybe I have bad luck, but every time I've 
dug into a dromaeo test in detail (admittedly only 4 different tests so 
far, but digging in detail takes a while) I've found that it was gated 
by weird things (substring() calls offset more than 16k characters into 
a string, cross-window function calls inside tight loops, that sort of 
thing) that I've seen nowhere outside dromaeo in the years I've been 
dealing with browser performance.  Said weird things, being weird, were 
not highly optimized for.  Now this is not to say the data was useless: 
in at least one of the cases we did some measurements and decided that 
the existing tuning was not reflecting web reality as well as it could; 
a side benefit was speeding up the relevant dromaeo test by 5x or so. 
But as Brendan keeps saying, we shouldn't be tuning to dromaeo; we 
should be tuning to the web.

This is a general issue with performance tests, computer and otherwise: 
tuning to the test.  Since it's inevitable for whatever we run on 
tinderbox, the goal should be to make sure that tuning to the test tunes 
to whatever we actually care about (which is not the test per se).

In the short run, testing _something_ DOM-related on tinderbox is better 
than not testing it at all, and dromaeo is here and ready to be used. 
This thread is about the slightly longer run.

-Boris