Pages with border-collapse and RGBA borders have very bad scrolling performance

[Chad von Nau]

I've made some examples to demonstrate some performance bugs with table rendering. 
These examples are the same content with different styling:

1) Normal scrolling. Solid borders and border-collapse:separate

 http://chadvonnau.com/projects/web/examples/webkit-table-bug/index.html

2) Slow scrolling. Solid borders and border-collapse:collapse

 http://chadvonnau.com/projects/web/examples/webkit-table-bug/bordercollapse.html

3) Very slow scrolling and beach ball of death.
   Semi-transparent RGBA borders and border-collapse:separate

 http://chadvonnau.com/projects/web/examples/webkit-table-bug/rgbaborders.html


I'm testing with Safari 5.1 and OS X 10.6.8 (+update) on my Late 2006 MacBook Pro.

Firefox 4 sees roughly equal performance on on all of those examples.
Safari 5.0 and earlier sees about the same performance on each example.
Chrome 13.0.7 has similar performance issues with these examples.

I reported what I believe to be the same issue to Google several months back. Here's my bug report with google:

 http://code.google.com/p/chromium/issues/detail?id=68215

Perhaps these issues may be coming from webkit code that Google has been using for a few months but only made it into Safari in 5.1.

Here is another page that exhibits performance problems because of border-collapse:collapse

 http://panlex.org/u

[Chad von Nau]

*** This bug has been marked as a duplicate of bug 34649 ***

[Simon Fraser (smfr)]

Reopening; the other bug is about DOM access.

[Chad von Nau]

Thanks, Simon. The two bugs seem related from my naive perspective. Was thinking this one might get resolved faster if it was merged with a bug that already had other people involved.

[Alexey Proskuryakov]

This appears to work nicely in current shipping Safari (I tested with Safari 7.1.4).

[Simon Fraser (smfr)]

I bet this scrolls horribly if it's changed to use overflow: scroll. I think we've regressed table border performance.