When Qt 5.9 LTS was launched, I wrote a blog post about Qt 5.9 performance, providing an overview of some of the areas with improved performance. These improvements benefit Qt users across all operating systems and processor architectures. The different processors and operating systems have unique characteristics that cause slight variations, but performance has practically always increased overall. In other words: With a new Qt version, you get more power out of an existing system. Performance improvements benefit both the users aiming to create an even fancier UI for their high-end system, as well as those who can now run Qt on lower-end hardware than before.
Also massively improved are the Qt Quick Controls. See the comparison between QML Bench tests of Qt Quick Controls below:
Qt 5.6.3 offers Qt Quick Controls 1, which was mainly aimed at desktop use cases. As it is a very convenient set of functionalities, many like to use Qt Quick Controls 1 in embedded devices too, which can sometimes make achieving the needed performance challenging. For this reason, we developed Qt Quick Controls 2 with embedded systems in mind. It again offers greatly improved performance in Qt 5.9.5 compared to previous versions. If there are some challenges to get Qt Quick Controls 1 running smoothly on an embedded system, using Qt Quick Controls 2 instead will most likely fix that problem as it is almost 8 times faster on average.
The third and final graph in this post summarizes all other areas of QML Bench tests:
Each of these categories contains multiple tests, and the results in the different areas as such are not directly comparable with each other. In order to see the improvements of Qt 5.9.5 relative to Qt 5.6.3, the results are normalized to show the Qt 5.6.3 results as 100. The graphs show that the improvements to all categories are quite significant and should be clearly noticeable for practically any Qt Quick / QML application.