https://doc.qt.io/archives/qt-5.6/qtquick-performance.html
In general, "property var" should be considered to be superior to "property variant" for every use-case from QtQuick 2.0 and newer (note that "property variant" is marked as obsolete), as it allows a true JavaScript reference to be stored (which can reduce the number of conversions required in certain expressions).
First of all: Take all measurements I mention with a grain of salt – all of them are rough and not necessarily measured more than a few times. All times were measured on an Xperia X run via SDK.
Visiting a chat page can take a long time, especially before the qml is cached by the engine.
When opening it for the first time after application launch, it sometimes takes >1000ms from onClicked (OverviewPage) to Component.OnCompleted (Chatpage).
Subsequent activations take roughly 470-480ms.
With these changes, I was able to reduce these times to ~450ms for the first, ~100ms for subsequent activations of the ChatPage on my test device.
Things changed:
- The components for displaying extra content to a message are (mostly) gone and replaced by a single Loader. This Loader does not use sourceComponent to trade the initial compilation boost for a neglegible bit of runtime penalty.
- Connections were consolidated
- I was surprised how costly the inclusion of the RemorseItem was (compiling ~75ms, initializing up to ~20ms for every delegate). So I traded a bit for a compromise. deleteMessageRemorseItem is now defined on the appWindow level, where it gets a bit mitigated by the animations at application start. Also, only one deletion at a time is now possible. We can easily revert this change, but I thought it worthwhile despite its drawbacks.
- profileThumbnailComponent is now defined directly as sourceComponent, removing the need for its id. Probably didn't do anything.
- InReplyToRow had width: parent.width, so I removed horizontalCenter. Also probably didn't change compilation time at all.
- Another compromise I was willing to take – your opinion may differ: The PickerPages took ages (~200ms) to just parse/compile inside those Components, so I replaced them with the "string notation" of pageStack.push. Drawback: The first time a picker gets activated, you'll see how slow it is. Subsequent activations aren't that bad – also for the other pickers.
