Closed Bug 166691 Opened 22 years ago Closed 1 year ago

tall tiled background images slow page scrolling when in body or table data element

Categories

(Core Graveyard :: Image: Painting, defect)

Product:
Core Graveyard
Component:
Image: Painting
Platform:
x86
Windows NT
Type:
defect
Priority:
Not set
Severity:
normal

Tracking

(Not tracked)

Status:
RESOLVED WORKSFORME

People

(Reporter: market, Unassigned)

References

(
URL
)

Details

(Keywords: perf) 

User-Agent:       Mozilla/5.0 (Windows; U; WinNT4.0; en-US; rv:1.1) Gecko/20020826
Build Identifier: Mozilla/5.0 (Windows; U; WinNT4.0; en-US; rv:1.1) Gecko/20020826

also related to:  85771  28578
I have tested it with several background images that have a width 
that requires tiling across some portion of the page AND that are much taller
than wide.
Happens whether in a <td background=image.gif> or in <body background=image.gif> 
cause very very slow _scrolling_, not loading, whenever the image is visible.  
It does not happen if the image to be tiled is say 5x5 pixels.  

So if it only in a <td> element, it is only slow when that table element is
visible. If it 
is in <body> it is slow all the time.  The slowness is accompanied by intense 
hard disk activity.  (In ns6.2 it is also slow, but there is no disk activity.)   

The offending background image at smalleranimals.com is 4 x 5000 and actually
loads nearly instantly, so that is not the issue, that page was picked because
it had no java script.  
 
If the image to be tiled is presented preexpanded instead, everything works as
it should.  


Reproducible: Always

Steps to Reproduce:
1. open a page with a background image that is substantially taller than it is wide.
2. scroll up or down.  Slower machines greatly amplify the effect.
3. Scroll with either the arrow keys or the scroll bar.  The length of the scroll
doen't matter, only the action of scrolling.

Actual Results:  
A 2 page document with the image takes 2.5 seconds to scroll while hard drive is
madly accessed.  Without the image,
scrolling the page is instanteous.  
Scrolling down the image in a page by itself causes no hesitation.  

Expected Results:  
scrolled instantly or nearly so.

Bugs 85771  28578 seem related, but are not the same.
In fact, it might be that fixing 85771 created the problem.
bug 85771
bug 28578

typed in bug names so bugzilla would turn them into links
Hmmm.  From your description, this sounds like a paging issue rather than an
image issue.  How much RAM do you have on your machine, and were you
memory-bound when you were testing?  The page is slightly jerky for me on Win2k,
but quite usable.

Please change the component of this bug to "Image: GFX"
Status: UNCONFIRMED → NEW
Ever confirmed: true
My CPU at 100%  RAM 256MB less than half in use during the attempt to scroll
(118K available).  I thought it was a paging issue at first, else why the disk
i/o?  But  
it scrolls through any other kind of web document just find.
Sorry that's 118000K Physical Memory Available
changed to Image:GFX
Component: Browser-General → Image: GFX
Tested on same machine in W98.  The whole thing is very slow, and the image
causes  additional slowdown, but no disk i/o.  (It speeded up dramatically when
I INCREASED from 8 bit colors to 16 bit colors.-- is that expected?) 
Tested on another faster C3 733 machine running W2K.  The page was jerky, but no
external paging.  May be idiosyncratic to my install of NT4.0 sp6a.
Blocks: 100951
->default contacts
Assignee: asa → jdunn
QA Contact: asa → tpreston
Keywords: perf
Assignee: jdunn → pavlov
QA Contact: tpreston
Assignee: pavlov → nobody
Product: Core → Core Graveyard
URL: http://www.smalleranimals.com/isource... → https://web.archive.org/web/200210170...
Status: NEW → RESOLVED
Closed: 1 year ago
Resolution: --- → WORKSFORME
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