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Bug 126344 - Undo is slower and consumes more CPU time after pressing undo (compared to 6.1)
Summary: Undo is slower and consumes more CPU time after pressing undo (compared to 6.1)
Status: NEW
Alias: None
Product: LibreOffice
Classification: Unclassified
Component: Writer (show other bugs)
(earliest affected)
Hardware: All Windows (All)
: medium normal
Assignee: Not Assigned
Keywords: bibisected, bisected, perf, regression, wantBacktrace
Depends on:
Blocks: Undo-Redo
  Show dependency treegraph
Reported: 2019-07-11 13:23 UTC by Telesto
Modified: 2020-06-08 19:54 UTC (History)
2 users (show)

See Also:
Crash report or crash signature:


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Description Telesto 2019-07-11 13:23:44 UTC
Undo is slower and consumes more CPU time after pressing undo (compared to

Steps to Reproduce:
1. Open attachment 140185 [details]
2. Press F5
3. Go to page 200
4. Set cursor at the beginning of pag 200
5. Press Shift & scroll to the bottom and select the end of the sentence (ergo select everything from pag 200 until end)
6. Press Delete (wait until the CPU usage is down to nearly zero)
7. Press Undo (CTRL+Z


Actual Results:
30 seconds CPU spike after press undo. It's slower and more CPU hogging

Expected Results:
12 seconds spike in LibO (comparison is bit off.. scheduling has changed.. everything is processed on 'high priority'.. previously the scheduling had more of idle way of doing things.. but it's to slow for sure.. Maybe large paragraphs issue

Reproducible: Always

User Profile Reset: No

Additional Info:
Version: (x86)
Build ID: 2f2f4767089512c34514896bc37823f9310e9dd4
CPU threads: 4; OS: Windows 6.3; UI render: default; VCL: win; 
TinderBox: Win-x86@42, Branch:master, Time: 2019-07-10_00:49:53
Locale: nl-NL (nl_NL); UI-Language: en-US
Calc: CL
Comment 1 Dieter 2019-07-11 17:17:10 UTC
I confirm it with attached document

Around 30 sec in

Version: (x64)
Build ID: ae823e4633a76d13cebc6432b9e44b9b2862326b
CPU threads: 4; OS: Windows 10.0; UI render: GL; VCL: win; 
TinderBox: Win-x86_64@42, Branch:master, Time: 2019-06-26_23:06:07
Locale: de-DE (de_DE); UI-Language: en-US
Calc: threaded

and around 17 sec in

Version: (x64)
Build-ID: c838ef25c16710f8838b1faec480ebba495259d0
CPU-Threads: 4; BS: Windows 6.19; UI-Render: GL; 
Gebietsschema: de-DE (de_DE); Calc: group
Comment 2 Buovjaga 2020-06-08 19:26:35 UTC
Bibisected with win32-6.2 to!/
Upgrade to ICU 62.1

So "nobody's fault". I also checked and automatic spellchecking does not have an effect on/off.