76299 - scrolling animation by setting style.top is extremely slow compared to IE and Netscape 4.x

Status: VERIFIED DUPLICATE of bug 70156

(Core :: DOM: CSS Object Model, defect)

Description

[robert giordano]

From Bugzilla Helper:
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; m18) Gecko/20010131
Netscape6/6.01
BuildID:    20010131

I created the page at http://dev.tvtaxi.com/tests/scroll.htm to compare the
speed of moving a <DIV> layer on different browsers. This page will demonstrate
how IE5 and Netscape 4.x are many, many times faster than Netscape 6. On the
Macintosh, Netscape 4.x is many times faster than Netscape 6 while IE5 is only
marginally faster, but faster nonetheless.

Reproducible: Always
Steps to Reproduce:
1.Go to the above listed URL and let the test run in IE5, Netscape 4.7, and then
Netscape 6.
2.
3.

Actual Results:  On a Pentium III, 1ghz, I obtained the following results:
1) Internet Explorer 5: 4.06 seconds
2) Netscape 4.7: 4.06 seconds
3) Netscape 6.01: 28.56 seconds

Expected Results:  I would have expected Netscape 6 to be at least as fast as
the other browsers

I tried a versions of the test page in quirks mode and standards mode and there
was no significant difference in the timings.

Comment 1

[Oliver Klee]

Adding perf keyword and over to DOM style for a guess.

Robert, Bugzilla is the Mozilla Bug Database. Could you try to reproduce this
with a recent Mozilla nightly build? Thanks!

Comment 2

[timeless]

[irrelvenat] that webserver is _slow_ 
168s = normal
130s = css forcefully disabled
132s = skipping first settimeout

5s=time to join 50 strings (no css)
0s = no scrolling no css skipping settimeout
--
scrolling 5times
<~7s [no css, skipping settimeout]
>~7s [for loop, no css]
[extrapolating gives me 70s, not 130.. hrm]
>~5s [while loop, no if]
--
scrolling 25times
<~36s [whileloop]
--
scrolling 50times - while loop, no timeout: 70s as extrapolated.

while (++count<5) {
  ty=ty-15
ss[count]=new Date().getTime();
  scrollObj.style.top=ty+"px"
}
the significant trailing digits of ss[]:
87324 88386 89908 91350 92702
[ie: 0...0]

my versions are available on http://timeless.student.umd.edu/mozilla/css/
in some versions, i broke compat w/ nc4 to see if the |if| was a 
significant factor

Comment 3

[Nick Rosier]

Confirmed with build 2001041704 on W2K

Comment 4

[Boris Zbarsky [:bzbarsky]]

Problem on Linux too (NS 4.x -- 4.5 seconds, Mozilla 115 seconds for the
nocss.htm page).  I'm using the 2001-04-17-08 nightly.

Comment 5

[saari (gone)]

I ran this through Quantify, and all I see are thousands and thousands and 
thousands of style operations and line layouts. Looks like we're probably 
tearing down and rebuiding everything and reresolving style along the way. Not 
good.

Comment 6

[Johnny Stenback (:jst)]

Saari, thanks for running this in quantify, I was gonna do that myself but you
beat me to it. I think this is a dup of one of attinasi's bugs related to
setting style properties being slow. Reassigning.

Comment 7

[timeless]

according to saari, the best page (that has the full 51x string and loops 50 
times) is nospan.htm which takes 36s (improved over 50 and 138 for some of the 
other versions).

Scrolling a document (even 50 times) shouldn't require changing its object 
model at all. [ie takes about 1/3 of a second to do the 50 scroll ops -- this 
might vary a bit depending on which testpage you try and system load]

Comment 8

[Marc Attinasi]

Sounds like bug 70156 - thanks.

*** This bug has been marked as a duplicate of 70156 ***

Comment 9

[Hixie (not reading bugmail)]

VERIFIED ensured DUPLICATE (copied keywords and URL)