Resizing an application using Qt Creator is buggy and laggy - qt

Question

So as the title says , I'm having trouble making my GUI stop being laggy, for example when I drag the left side of the GUI it stretch's in a weird way and has slow animation , also my cursor reaches the point before the GUI and it takes like half a second to reach the exact shape that is wanted.
this the case for the four 8 possible resizing options (left,right,bottom right etc ..) .
I'm using Qt Creator and writing in QML .
and I'm using this function to resize :
mainWindow.startSystemResize("some edge");
and the following flags are applied to the window application:
flags: Qt.Window | Qt.FramelessWindowHint
Edit
So I made the following example code and it has the same kind of problem :
import QtQuick 2.15
import QtQuick.Window 2.15
import QtQuick.Controls 2.15
Window {
id: mainWindow
width: 1000
height: 580
minimumWidth: 800
minimumHeight: 500
visible: true
color: "#00000000"
title: qsTr("Test")
//removing the windows default bar
flags: Qt.Window | Qt.FramelessWindowHint
Rectangle {
id: bg
color: "#2c313c"
anchors.fill: parent
Rectangle {
id: rectangle
x: 205
y: 133
width: 200
height: 200
color: "#e03d3d"
anchors.verticalCenter: parent.verticalCenter
anchors.horizontalCenter: parent.horizontalCenter
}
}
//for resizing using the mouse
property int bw: 5
MouseArea {
id: resizingWindow
anchors.fill: parent
hoverEnabled: true
cursorShape: {
const p = Qt.point(mouseX, mouseY);
const b = bw + 10; // Increase the corner size slightly
if (p.x < b && p.y < b) return Qt.SizeFDiagCursor;
if (p.x >= width - b && p.y >= height - b) return Qt.SizeFDiagCursor;
if (p.x >= width - b && p.y < b) return Qt.SizeBDiagCursor;
if (p.x < b && p.y >= height - b) return Qt.SizeBDiagCursor;
if (p.x < b || p.x >= width - b) return Qt.SizeHorCursor;
if (p.y < b || p.y >= height - b) return Qt.SizeVerCursor;
}
// acceptedButtons: Qt.NoButton // don't handle actual events
DragHandler {
id: resizeHandler
// grabPermissions: TapHandler.TakeOverForbidden
target: null
onActiveChanged: if (active) {
const p = resizeHandler.centroid.position;
const b = bw + 5; // Increase the corner size slightly
let e = 0;
if (p.x < b) { e |= Qt.LeftEdge }
if (p.x >= width - b) { e |= Qt.RightEdge }
if (p.y < b) { e |= Qt.TopEdge }
if (p.y >= height - b) { e |= Qt.BottomEdge }
mainWindow.startSystemResize(e);
}
}
}
}
PS:
In order to run this you need to put the code in Qt Creator and then run the QML code and try to resize in one the 8 directions