Repeated pasting performance issues in QLineEdit, QTextEdit

When copying text from any application except the one in question, and pasting it repeatedly into a QLineEdit or QTextEdit via holding down CTRL+V, the pasting is not smooth, but rather jumpy and puts a more than usual load on the CPU.

To the contrary, doing the same thing by copying text inside the same program, and then holding CTRL+V the pasting is quite fast, smooth and does not raise the CPU level much at all.