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#1 2015-06-16 07:42:53

kokoko3k
Member
Registered: 2008-11-14
Posts: 1,825

qt4 updated to 4.8.7: Slow text scrolling and higher load time.

System is fully upgraded, and i just noticed that every qt4 application has become incredibly slow when using QT_GRAPHICSSYSTEM=native (slow dolphin scrolling, slow konsole scrolling)
It is probably related to text antialiasing, because if i disable subpixel hinting in konsole, it start to scroll fast.

Reverting back to 4.8.6 fixes it.

I want to use native instead of raster because:
1) when used remotely via x2go and ssh, qt apps are very fast using QT_GRAPHICSSYSTEM=native
2) with QT_GRAPHICSSYSTEM=native one is able to retain RGB subpixel hinting even over trasparent windows.

I'm using nvidia-340xx 340.76 with a geforce 9800GT and  freetype2-infinality 2.4.12-2 if it matters.


Anybody can help please?

-EDIT

This does not seem to be related to an update of the xorg-server, nor to the graphic driver; i notice the same behaviour when using a remote (fast) vnc connection.
I bet it is a QT4 bug; someone could test please?

Last edited by kokoko3k (2015-06-19 15:56:35)

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#2 2015-06-19 12:48:54

kokoko3k
Member
Registered: 2008-11-14
Posts: 1,825

Re: qt4 updated to 4.8.7: Slow text scrolling and higher load time.

It is not just the text scrolling under native graphicssystem to be slow.
All qt4 apps with text edit widgets are now slower to open, even with raster graphicssystem.
Gambas3 ide takes 6 seconds to start; on 4.8.6 it starts in 2 seconds here.

Just reported both:

https://bugreports.qt.io/browse/QTBUG-46700
https://bugreports.qt.io/browse/QTBUG-46778

Last edited by kokoko3k (2015-06-19 15:57:14)

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#3 2016-03-08 08:59:04

kokoko3k
Member
Registered: 2008-11-14
Posts: 1,825

Re: qt4 updated to 4.8.7: Slow text scrolling and higher load time.

Oh well, if anyone cares about speed, i made a PKGBUILD that reverts the commit causing the slowness.
https://github.com/qtproject/qt/commit/ … a0946addd7

https://aur.archlinux.org/packages/?O=0 … ert80e3108

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