QWebEnginePage contents size is resize slowly when the window is resizing

5.6.2 has no api to get page contentsSize, but it is the same result.

when I double click the window title to zoom the window, the page contentSize only change at the last time (window zoomed completely). And there is no api to allow me to change the contentSize dynamic

here is the result print in resizeEvent under 5.7.1
WebView PyQt5.QtCore.QSize(904, 702) Page ContentSize PyQt5.QtCore.QSizeF(900.0, 700.0)
WebView PyQt5.QtCore.QSize(918, 708) Page ContentSize PyQt5.QtCore.QSizeF(900.0, 700.0)
WebView PyQt5.QtCore.QSize(986, 734) Page ContentSize PyQt5.QtCore.QSizeF(900.0, 700.0)
WebView PyQt5.QtCore.QSize(1032, 752) Page ContentSize PyQt5.QtCore.QSizeF(900.0, 700.0)
WebView PyQt5.QtCore.QSize(1089, 774) Page ContentSize PyQt5.QtCore.QSizeF(900.0, 700.0)
WebView PyQt5.QtCore.QSize(1227, 828) Page ContentSize PyQt5.QtCore.QSizeF(900.0, 700.0)
WebView PyQt5.QtCore.QSize(1305, 859) Page ContentSize PyQt5.QtCore.QSizeF(900.0, 700.0)
WebView PyQt5.QtCore.QSize(1471, 924) Page ContentSize PyQt5.QtCore.QSizeF(900.0, 700.0)
WebView PyQt5.QtCore.QSize(1630, 986) Page ContentSize PyQt5.QtCore.QSizeF(900.0, 700.0)
WebView PyQt5.QtCore.QSize(1838, 1067) Page ContentSize PyQt5.QtCore.QSizeF(900.0, 700.0)
WebView PyQt5.QtCore.QSize(1968, 1117) Page ContentSize PyQt5.QtCore.QSizeF(900.0, 700.0)
WebView PyQt5.QtCore.QSize(1998, 1129) Page ContentSize PyQt5.QtCore.QSizeF(900.0, 700.0)