Since upgrading from Qt 5.15 to 6.8.4 our application feels very sluggish. 

It's hard to quantify the difference, but since upgrading UI animations look slow/choppy, and there is a noticeable lag in touchscreen event-handling.

We have a device based on an NVidia Jetson TX2. 
Our OS is a custom Yocto/kirkstone with Qt 6.8.4 and meta-tegra 32.7.6. 

So far I've looked at CPU- and GPU load and cannot find anything out of the ordinary. There is hardly any difference with Qt5.
CPU-load is around 40% (with 4/6 CPUs enabled). GPU-load is on average 50%, but has dips and peaks to 10% and 97% (we do a lot of processing on the GPU).