Qt5's WebKit is 4000 times slower than 4.7/4.8 when reading C++ object in Javascript



  • I've recently ported one of my programs written for 4.7/4.8 to version 5, and noticed some code is running very slow.

    What my program needs to do is to construct a list of objects in C++ (20K items), and in Javascript read the list "directly" by using "addToJavaScriptWindowObject"

    I think it has something to do with in the JS engine or new webkit.

    some task took 0.1 sec in Qt 4.7, while in Qt 5.3 needs 400 seconds now!!

    Can someone help me?

    In the meantime, I'm trying to install 4.8 version back but can't find the installer that includes qcreator and other things. The one I can find doesn't include qcreator. If I install qcreator separately, I can't config it properly because I can't add the qt version install in /usr/bin/qmake4.8.....just can't see the path with the UI.


  • Moderators

    Don't install to system folders, then. Run the installer as normal user and install in $HOME.

    Qt Creator can work with any number of concurrently installed/ compiled Qt versions, so you can safely use the one that came with Qt 5.3.



  • I see. But how can I do that given a .dmg file?

    http://download.qt-project.org/official_releases/qt/4.8/4.8.6/qt-opensource-mac-4.8.6-1.dmg

    [quote author="sierdzio" date="1405576953"]Don't install to system folders, then. Run the installer as normal user and install in $HOME.

    Qt Creator can work with any number of concurrently installed/ compiled Qt versions, so you can safely use the one that came with Qt 5.3.[/quote]


  • Moderators

    Sorry, I have assumed yoy are working on Linux. Then possibly you have 2 options: symlink /usr/bin/qmake4.8 to /usr/bin/qmake, or compile Qt from source and put it exactly where you want to. The precompiled installers on Mac put Qt files all over the OS, which - in my opinion - is very wrong. When compiling from source, you can set it up so that all files remain within a single directory, and you can keep many Qt versions in parallel.



  • Yes, I think that's very wrong too.

    QCreator doesn't allow me to "select" symlink......

    [quote author="sierdzio" date="1405580594"]Sorry, I have assumed yoy are working on Linux. Then possibly you have 2 options: symlink /usr/bin/qmake4.8 to /usr/bin/qmake, or compile Qt from source and put it exactly where you want to. The precompiled installers on Mac put Qt files all over the OS, which - in my opinion - is very wrong. When compiling from source, you can set it up so that all files remain within a single directory, and you can keep many Qt versions in parallel.[/quote]



  • I don't understand why Qt doesn't have a "normal" 4.8 installer for download...


  • Moderators

    [quote author="kenjichanhkg" date="1405599776"]I don't understand why Qt doesn't have a "normal" 4.8 installer for download...[/quote]

    I think it's because all the effort is put into Qt 5. Qt 4 receives only bug fixes.


Log in to reply
 

Looks like your connection to Qt Forum was lost, please wait while we try to reconnect.