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Re: [css3-flexbox] Fixing the "replaced elements may or may not be inline" issue

From: Boris Zbarsky <bzbarsky@MIT.EDU>
Date: Wed, 27 Jun 2012 12:50:42 -0400
Message-ID: <4FEB39E2.8080204@mit.edu>
To: www-style@w3.org
On 6/27/12 12:18 PM, Alex Mogilevsky wrote:
> These are real issues the code has to deal with, but there is no evidence that it is a problem for performance.

It's a problem only insofar as it disables a certain class of 
optimizations that are now possible and that some UAs do in fact 
perform.  For example, right now it's possible to share computed display 
data across nodes that have the same rules applying to them, no matter 
what their parents are.  This is in fact a feature that non-inherited 
properties in CSS have in common for the most part, and is the basis for 
a number of optimizations at least in Gecko.

Now we can obviously revisit those optimizations, but just disabling 
them naively is _guaranteed_ to be a problem for both memory usage 
(because it will disable the sharing, forcing a lot more data to be 
stored in memory) and for performance (because the data that is shared 
right now obviously only needs to be computed once).

The last time I ran the numbers on a change along these lines, I 
measured 5-10% difference in pageload performance.  If that counts as 
"evidence".

-Boris

P.S.  I don't have a strong opionion on the matter at hand, since I 
haven't really been following the discussion, to be honest.  Obviously, 
with enough code complexity we can always make this work on our end...
Received on Wednesday, 27 June 2012 16:51:16 GMT

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