Good afternoon!
I noticed the plot's strange behavior while dragging or zooming QCPCurve items. There is a wrong point connection in curves in the plot. Some segments of the curve are jumping during axes dragging or else disappearing.
There is a reference to an optimization in the documentation.
QCPCurve:: draw to generate a point vector (pixels) which represents the line of the curve. Line segments that aren't visible in the current axis rest are handled in an optimized way.
So, I inherited QCPCurve and changed draw function to paint all the data in the curve.