https://bugs.freedesktop.org/show_bug.cgi?id=63656
Priority: medium
Bug ID: 63656
Assignee: [email protected]
Summary: sever performance especially with complex fonts
Severity: critical
Classification: Unclassified
OS: All
Reporter: [email protected]
Hardware: All
Status: UNCONFIRMED
Version: 4.0.2.1 rc
Component: Libreoffice
Product: LibreOffice
There is a severe performance issue in all of the LibreOffice suit which I
believe to be related to the font rendering mechanism. The application (Write,
Calc, whatever,) hangs even more when using complex fonts and/or large
documents.
A friend of mine, that is Khaled Hosny, the previous leader of the Arabic
localization team of Gnome project, and who currently works in font design,
mentions that the fonts engine used in LibreOffice is the the source of this
performance issue.
This is a part of the conversation, where he uses the Amiri font to compare the
performance of the engine that is used in LibreOffice to HarfBuzz :
---------------
(IDT 10:43:03 ) KhaledHosny:
time hb-shape amiri-regular.ttf --text-file=test-suite/ar.txt
--num-iterations=500 --shapers=icu_le
(IDT 10:43:14 ) KhaledHosny:
real 2m53.594s
(IDT 10:43:15 ) KhaledHosny:
user 2m53.331s
(IDT 10:43:16 ) KhaledHosny:
sys 0m0.040s
(IDT 10:43:28 ) KhaledHosny:
[[ This is the fonts engine that is used in LibreOffice ]]
(IDT 10:43:54 ) KhaledHosny:
time hb-shape amiri-regular.ttf --text-file=test-suite/ar.txt
--num-iterations=500
(IDT 10:44:05 ) KhaledHosny:
real 0m9.520s
(IDT 10:44:06 ) KhaledHosny:
user 0m9.393s
(IDT 10:44:06 ) KhaledHosny:
sys 0m0.016s
(IDT 10:44:21 ) KhaledHosny:
[[ And this one is HarfBuzz, do you see the difference ?? ]]
-----------------
The difference is unbelievable !!
By the way, he says that he worked on porting LibreOffice to HarfBuzz long time
ago, and that there are some remaining issues that he couldn't fix due to the
lack of time.
You can find some relevant notes and a patch in this link:
http://lists.freedesktop.org/archives/libreoffice/2012-October/040350.html
He also mentions that he welcomes any questions that are relevant to this
issue.
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