Bug 43809 - Degraded performance updating <tspan> due to excessive repaint
Summary: Degraded performance updating <tspan> due to excessive repaint
Status: NEW
Alias: None
Product: WebKit
Classification: Unclassified
Component: SVG (show other bugs)
Version: 528+ (Nightly build)
Hardware: Mac (Intel) OS X 10.6
: P2 Enhancement
Assignee: Nobody
URL:
Keywords: InRadar
Depends on:
Blocks:
 
Reported: 2010-08-10 14:40 PDT by Tony Sung
Modified: 2011-07-06 11:38 PDT (History)
4 users (show)

See Also:

Attachments
Primary test case (5.99 KB, application/zip)
2010-08-10 14:42 PDT, Tony Sung 		no flags Details
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Description Tony Sung 2010-08-10 14:40:17 PDT 
Open the attached test case, which by default shows 60 lines of text and which the first line of text is updated continuously with a setTimeout(func, 0) call.

There're 3 cases, where the DOM structures are all the same but having the first 2, 60, or 200 <tspan> visible. In the test cases all except the first <tspan> is static.

Compare the frame rates of the 3 cases with the help of QuartzDebug. The more number of visible <tspan> we have, the slower the frame rate it is, even though we're changing only one of the <tspan> in all 3 cases.

Enabling "Flash Screen Updates" in QuartzDebug suggests that the browser is repainting all <tspan> including those which haven't been changed.
Comment 1 Tony Sung 2010-08-10 14:42:01 PDT 
Created attachment 64044 [details]
Primary test case
Comment 2 Tim Horton 2011-07-06 11:38:01 PDT 
<rdar://problem/8293628>