I’ve done some profiling on my arale and I’ve found out a few interesting things:
- there’s an urlChanged handler in NavigationBar.qml¹ that’s triggered with every load event, and it’s costly - the loadEvent and titleChanged handlers in Browser.qml² are expensive too, because they cause updates to the HistoryModel that block the UI thread - the layout of the chrome/address bar depends too much on the 'loading'³ and 'loadProgress' properties of the webview, causing countless binding evaluations and re-layouts for each load event All those observations cause a tremendous slowdown on that specific page because scrolling triggers LoadCommitted events. I’m not sure why those events are triggered at all, but I’m sure the browser can be improved to not grind to a halt when that happens. ¹ https://bazaar.launchpad.net/~phablet-team/webbrowser-app/trunk/view/head:/src/app/webbrowser/NavigationBar.qml#L142 ² https://bazaar.launchpad.net/~phablet-team/webbrowser-app/trunk/view/head:/src/app/webbrowser/Browser.qml#L1276 ³ https://bazaar.launchpad.net/~phablet-team/webbrowser-app/trunk/view/head:/src/app/webbrowser/NavigationBar.qml#L125 ** Changed in: webbrowser-app (Ubuntu) Assignee: (unassigned) => Olivier Tilloy (osomon) ** Changed in: webbrowser-app (Ubuntu) Importance: Undecided => High -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to webbrowser-app in Ubuntu. https://bugs.launchpad.net/bugs/1611680 Title: Scrolling on www.ceskenoviny.cz is very slow Status in webbrowser-app package in Ubuntu: Confirmed Bug description: Hello, the Czech news site I am reading quite often was recently updated to a new design and as of this update scrolling on the site gets quite tricky. On some articles scrolling is almost impossible. Now this is not the first site I find difficult to scroll on with an Ubuntu's web browser unfortunately, though it is usually the case of some heavy javascript ballast on the site I am sure. The worst experience I am getting so far is on this article: http://www.ceskenoviny.cz/zpravy/francouzska-justice-obvinila-16letou- divku-z-planovani-teroru/1379685 where scrolling is very laggy and more or less only gets me either to the absolute top or the absolute bottom of the article, not anywhere in the middle. Slow scrolling won't help the issue. Other articles like this one http://www.ceskenoviny.cz/zpravy/ceske- drahy-dostaly-pokutu-150-000-kc-za-chybejici-ceniky/1380181 feels only very laggy but not that bad from my experience. I've been testing this on my Meizu MX4 with rc-proposed. Maybe this is only the device issue though I doubt it. Is there something you can do about it? Thank you very much. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/webbrowser-app/+bug/1611680/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
