Bug 74373 - UI: Slightly increased Xorg CPU usage with 'marching ants' on hidden Calc window
Summary: UI: Slightly increased Xorg CPU usage with 'marching ants' on hidden Calc window
Status: RESOLVED WORKSFORME
Alias: None
Product: LibreOffice
Classification: Unclassified
Component: Calc (show other bugs)
Version:
(earliest affected)
4.1.4.2 release
Hardware: All All
: medium minor
Assignee: Not Assigned
URL:
Whiteboard:
Keywords: perf
Depends on:
Blocks: Cell-Selection
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Reported: 2014-02-02 12:29 UTC by dg1727
Modified: 2025-05-10 15:15 UTC (History)
4 users (show)

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Description dg1727 2014-02-02 12:29:39 UTC 
1.  Open or create a Calc document.  
2.  Maximise the window.  
3.  Drag-select a large area of cells (no need to go outside the visible window).  
4.  Press Ctrl-c to copy those cells & start the 'marching ants' border around them.  
5.  Create a new Calc document and maximise its window, or otherwise bring up a maximised window that covers the first Calc window.  
6.  Issue:  Even though the first Calc window is no longer displayed, the Xorg CPU usage is slightly increased by the 'marching ants' effect.  The %CPU increase is more noticeable on slow computers.  

LibreOffice 4.1.4.2 on Ubuntu 13.04.
Comment 1 dg1727 2014-02-02 12:39:55 UTC 
This bug is probably related to bug 73841 but suggests an optimisation that might not be obvious from that bug (not having X animate the "marching ants" when the window isn't shown).
Comment 2 John Ayo 2014-02-03 09:26:36 UTC 
I have noticed this in the Windows version as well, but with very noticeable effects on the speed of other running programs. This is on a system with a Celeron D processor.
Comment 3 Robinson Tryon (qubit) 2015-01-15 00:08:41 UTC 
TESTING with LO 4.4.0.2 + Ubuntu 14.04

(In reply to dg1727 from comment #0)
> 1.  Open or create a Calc document.  
> 2.  Maximise the window.  
> 5.  Create a new Calc document and maximise its window, or otherwise bring
> up a maximised window that covers the first Calc window.  

With 2 Calc windows open and maximized (with nothing in them except a small label in A1 to tell them apart, X.org CPU usage as reported by top was:
1-3 %

> 3.  Drag-select a large area of cells (no need to go outside the visible
> window).  
> 4.  Press Ctrl-c to copy those cells & start the 'marching ants' border
> around them.  
> 6.  Issue:  Even though the first Calc window is no longer displayed, the
> Xorg CPU usage is slightly increased by the 'marching ants' effect.  The
> %CPU increase is more noticeable on slow computers.  

With one of the windows fully selected (A1:P38 -- hey, that's a can opener! :-), copied (with CTRL-C), and hidden behind the other one, X.org CPU usage was around:
25-28 %

So I'll call this one CONFIRMED.
Status -> NEW

In fact, I wouldn't call that a "slight increase" in X.org CPU usage -- it's a significant increase, so:
Whiteboard -> perf
Comment 4 Robinson Tryon (qubit) 2015-12-09 18:08:25 UTC Comment hidden (obsolete)
Comment 5 QA Administrators 2017-01-03 19:41:23 UTC Comment hidden (obsolete)
Comment 6 Thomas Lendo 2019-09-08 21:30:52 UTC 
I noticed an increase of cpu usage up to 25% for very few seconds.
Comment 7 QA Administrators 2021-09-08 03:42:18 UTC Comment hidden (obsolete)
Comment 8 QA Administrators 2023-09-09 03:06:23 UTC Comment hidden (obsolete)
Comment 9 Buovjaga 2025-05-10 15:15:07 UTC 
In bug 56613 there is a reference to commit 5749afcc71438190853267029ee17d636c2cc910 which says:

"update the ants only twice per second
This fixes some performance problem when the whole sheet has been
selected. Updating the whole paint range 6 times per second seems
excessive."

Probably we can close this.