The attached project is set up to compare Qt Charts vs. Qt Graphs.

Steps to test

1. Build and run the attached project
2. Use `top` to monitor the app's CPU load while the line is being painted. Keep monitoring as the plot is filled + cleared a few times.
3. Set the Plot Type to "No Plot" to see the app's background CPU load
4. Repeat the test after changing "Graphs" to "Charts" (under the "Compile-time configuration" section in CMakeLists.txt)

Results

These are the numbers on the pre-built Boot to Qt 6.8.4 on Raspberry Pi 4, when updating the plot every 250ms (with 50 points appended per update, up to a total of 5000 points):

Notes:

• In "No Plot" mode, the QList<QPointF>s are still being modifed. We only omit the call to QXYSeries::append().
• "Start of Plot" is when the LineSeries is almost empty
• "End of Plot" is when the LineSeries is almost full
• Similar trends can be seen on Windows 10 (Intel HD Graphics 630 GPU), by increasing the number of samples and decreasing the update interval