slow QTreeWidget.clear

import sys
from PySide6.QtWidgets import QApplication, QMainWindow, QWidget, QVBoxLayout, QTreeWidget, QTreeWidgetItem, QPushButton, QSpinBox
from PySide6.QtGui import QPalette, QColor


class MainWindow(QMainWindow):

    def __init__(self):
        super(MainWindow, self).__init__()

        self.setWindowTitle("My App")

        layout = QVBoxLayout()

        self.t = QTreeWidget()

        b = QPushButton('clear tree')
        b.clicked.connect(self.clr)

        self.n = n = QSpinBox()
        n.setMaximum(1000000)
        n.setValue(1000)

        a = QPushButton('Add items')
        a.clicked.connect(self.add)

        layout.addWidget(self.t)
        layout.addWidget(n)
        layout.addWidget(a)
        layout.addWidget(b)

        widget = QWidget()
        widget.setLayout(layout)
        self.setCentralWidget(widget)

    def add(self):
        count = self.n.value()
        if count:
            items = [QTreeWidgetItem([]) for i in range(count)]

            self.t.addTopLevelItems(items)

    def clr(self):
        from time import perf_counter
        count = self.t.topLevelItemCount()
        t1 = perf_counter()
        self.t.clear()
        t2 = perf_counter()
        print(f'{count=} took {t2-t1}')


app = QApplication(sys.argv)

window = MainWindow()
window.show()

app.exec_() 

count=1000 took 0.001806599997507874
count=10000 took 0.02987070000017411
count=100000 took 1.43678160000126