416673 - Page zoom extremely slow on Web Trend Map (informationarchitects.jp)

Status: RESOLVED DUPLICATE of bug 449046

(Core :: Layout, defect)

Description

[Elmar Ludwig]

Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9b4pre) Gecko/2008021004 Minefield/3.0b4pre ID:2008021004

Changing the page zoom on the "Web Trend Map 2008 Beta" (see URL field) is extremely slow for me. Zooming in one step takes around 50 seconds here.

Steps to reproduce:

1. go to http://informationarchitects.jp/web-trend-map-2008-beta/
2. zoom in (via menu or Ctrl +)
3. reset zoom (via menu or Ctrl 0)

Both steps 2 and 3 take around 50 seconds each on my machine (Linux, 2.0 GHz P4, 512MB RAM). Zooming other pages takes at most 1-2 seconds.

Note: I have no idea what component to put this into, so I'm filing this in Firefox/General for now. This probably belongs somewhere into Core, but I don't know if this is Layout, GFX or something else.

Comment 1

[Jo Hermans]

It's caused by the 'Who cares' section on the lower right, the list of trackback entries. It's basically a very long paragraph with a very large number of spans, that has to flow into a narrow column, and this cases a great number of reflows. Even loading the initial page is very slow, although not as slow as when zooming.

A workaround is to place <li> tags before each trackback entry (thus before each <span>), since it's included in a <ol>..</ol> pair, but that is not really used.

The reason for the slowdown seems to be this CSS-rule :

.commentlist .trackbacksSup {
	font-variant: small-caps;
	text-transform: lowercase;
	}

Note that the text-transform is a bit superfluous when combined with small-caps, but that's not the problem. The 'small-caps' variant is the reason why so much cpu is used, in combination with the numerous reflows.

Comment 2

[Elmar Ludwig]

Even just moving the mouse over the "Who cares" links shows a lot of lag, it takes a few seconds for the link highlighting and cursor changes to catch up each time I move the mouse. Removing the "font-variant: small-caps;" via the DOM inspector indeed speeds things up considerably.

Comment 3

[Martijn Wargers (dead)]

Yeah, I agree this is probably the same as bug 449046.
Sorry for not noticing this earlier.

Comment 4

[Elmar Ludwig]

Fixed by checkin for bug 430332, so this was the same issue as bug 449046.