position:fixed slows Mozilla

Erik Sandblom

Hello

I'm trying to make some tooltips which are position:fixed. It works fine in
Opera and Safari/Konqueror, but in Firefox and Camino (ie Mozilla), it takes
a few seconds for each tooltip to display, and then to get hidden. If I use
position:absolute, the problem goes away, but the tooltips move around with
the containing, scrolling div.

..scroll { height: 400px; overflow: auto; }

http://transrail.se/new/ref-erik/

There are some missing alt tags so it doesn't validate, but I doubt that's
the problem.

Help! I hate browsers...

--
Erik Sandblom
my site is EriksRailNews.com

Jul 23 '05 #1

Jim Ley

On Wed, 09 Mar 2005 16:53:25 +0100, Erik Sandblom
<er***@operamail.com> wrote:

I'm trying to make some tooltips which are position:fixed. It works fine in
Opera and Safari/Konqueror, but in Firefox and Camino (ie Mozilla), it takes
a few seconds for each tooltip to display, and then to get hidden. If I use
position:absolute, the problem goes away, but the tooltips move around with
the containing, scrolling div.

any fixed elements severely impact performance in all browsers, think
about what has to happen, and I hope it'll be obvious why.

The solution is to not use fixed elements - or pick a faster browser.

Jim.
--
comp.lang.javascript FAQ - http://jibbering.com/faq/

Jul 23 '05 #2

Erik Sandblom

i artikel 42***************@news.individual.net, skrev Jim Ley på
ji*@jibbering.com den 05-03-09 17.10:

any fixed elements severely impact performance in all browsers, think
about what has to happen, and I hope it'll be obvious why.

I don't get it. If it's fixed, it's always in the same place, so no
computation is necessary. Shouldn't fixed actually be faster?

--
Erik Sandblom
my site is EriksRailNews.com

Jul 23 '05 #3

Jim Ley

On Wed, 09 Mar 2005 17:52:41 +0100, Erik Sandblom
<er***@operamail.com> wrote:

i artikel 42***************@news.individual.net, skrev Jim Ley på
ji*@jibbering.com den 05-03-09 17.10:

any fixed elements severely impact performance in all browsers, think
about what has to happen, and I hope it'll be obvious why.

I don't get it. If it's fixed, it's always in the same place, so no
computation is necessary. Shouldn't fixed actually be faster?

Paint a picture. Now place a photograph on top of it, does it take
more effort to leave the photograph in place on the page or have it
move in line with the part of the picture you're looking at.

Jim.
--
comp.lang.javascript FAQ - http://jibbering.com/faq/

Jul 23 '05 #4

Peter1968

"Jim Ley" <ji*@jibbering.com> wrote in message
news:42***************@news.individual.net...

On Wed, 09 Mar 2005 17:52:41 +0100, Erik Sandblom
<er***@operamail.com> wrote:

i artikel 42***************@news.individual.net, skrev Jim Ley på
ji*@jibbering.com den 05-03-09 17.10:

any fixed elements severely impact performance in all browsers, think
about what has to happen, and I hope it'll be obvious why.

I don't get it. If it's fixed, it's always in the same place, so no
computation is necessary. Shouldn't fixed actually be faster?

Paint a picture. Now place a photograph on top of it, does it take
more effort to leave the photograph in place on the page or have it
move in line with the part of the picture you're looking at.

Jim.
--

Depends, can you see the painting at all? Is the photograph on top smaller
than the painting? Is the colour combination jarring? C'mon Jim, you have
to know these things, after all, one of the strengths of this particular
newsgroup is the rigid adhering to precision.

Jul 23 '05 #5

phil_gg04

>> any fixed elements severely impact performance in all browsers,
think

about what has to happen, and I hope it'll be obvious why.

I don't get it. If it's fixed, it's always in the same place, so no
computation is necessary. Shouldn't fixed actually be faster?

This is all horribly complicated. For example, if I have a page that
contains just a narrow column of text down the left hand side and I
scroll it, do all the white pixels in the right portion of the page get
moved around? (There's no need to move them.) It comes down to how
much effort is needed to work out what needs to move and balancing that
against "just moving everything". My experience is that Mozilla's
performance with repainting around position:fixed elements is about the
same as repainting around windows (e.g. dialogs) from other
applications that are on top of it, i.e. nothing to worry about.

Be careful though as there are some nasty bugs in Mozilla related to
position:fixed elements when you try to move them using things like
:hover and javascript. Some are improved in 1.8b1 but not all. Opera
also has bugs with postion:fixed.

--Phil.

Jul 23 '05 #6

David Ross

--

David E. Ross
<URL:http://www.rossde.com/>

I use Mozilla as my Web browser because I want a browser that
complies with Web standards. See <URL:http://www.mozilla.org/>.

Jul 23 '05 #7

David Ross

Erik Sandblom wrote:

Hello

I'm trying to make some tooltips which are position:fixed. It works fine in
Opera and Safari/Konqueror, but in Firefox and Camino (ie Mozilla), it takes
a few seconds for each tooltip to display, and then to get hidden. If I use
position:absolute, the problem goes away, but the tooltips move around with
the containing, scrolling div.

.scroll { height: 400px; overflow: auto; }

http://transrail.se/new/ref-erik/

There are some missing alt tags so it doesn't validate, but I doubt that's
the problem.

Help! I hate browsers...

This might be a symptom of Mozilla bug #124150. See
<URL:https://bugzilla.mozilla.org/show_bug.cgi?id=124150>.

--

David E. Ross
<URL:http://www.rossde.com/>

I use Mozilla as my Web browser because I want a browser that
complies with Web standards. See <URL:http://www.mozilla.org/>.

Jul 23 '05 #8