PyQtGraph. Increase fps when displaying 4.2 MPixels image?

Question

Python

Hello!
Wrote an application for displaying video from a 4.2 MPixels scientific camera. However, fps for this resolution is about 6. Examples of SpeedTest_Video for pyqtgraph at large values ​​give the same result. Does anyone have any ideas how to speed up the whole thing (fine tuning is important in the work)? Newbie in programming.
To test the application, the image is replaced by the intensity function, the speed of creating the grab_image() array in this code coincides with the speed of obtaining an image from a camera with a minimum exposure. A color card is required. The app has buttons and more, but I don't draw them for testing purposes.

import sys

import matplotlib.pyplot as plt
import numpy as np

from pyqtgraph.Qt import QtCore, QtGui
import pyqtgraph as pg
from PyQt5.QtWidgets import QMainWindow
from MineGUI import Ui_Dialog
from pyqtgraph.ptime import time


class MainWindow(QMainWindow, Ui_Dialog):
    def __init__(self, parent=None, *args, **kwargs):
        QMainWindow.__init__(self)
        self.setupUi(self)

def main():
    # Init main window window
    app = QtGui.QApplication([])
    main = MainWindow()
    main.show()
    # Add ViewBox for Image
    view = pg.ViewBox()
    main.imshow.setCentralItem(view) # (main.imshow = pg.GraphicsView(Dialog) from MineGUI)
    # Add Image Item and set colormap
    img = pg.ImageItem()
    cmap = pg.ColorMap(bit, colmap)
    lut = cmap.getLookupTable(0.0, 1.0, 255)
    img.setLookupTable(lut)
    img.setAutoDownsample(True)
    img.setBorder('b')
    
    view.addItem(img)


    timer = QtCore.QTimer()

    def setText(qo):
        main.exposValue.setText(str(qo)) #(main.exposValue = QtWidgets.QLabel(Dialog) from MineGUI)

    def grab_image():
        wx = 720 + np.random.rand(1) * 20
        wy = 650 + np.random.rand(1) * 30
        return intensity(x, wx, wy)

    def intensity(x, wx, wy):
        zx = np.exp(-2 * (x[None, :] - 1000) ** 2 / wx ** 2)
        zy = np.exp(-2 * (x[:, None] - 1000) ** 2 / wy ** 2)
        return (zx * zy)

    global lastTime, fps
    lastTime = time()
    fps = None
    x = np.arange(0, 2048, 1)

    def update():
        global lastTime, fps, data

        data = grab_image()
        img.setImage(data)

        now = time()
        dt = now - lastTime
        lastTime = now

        if fps is None:
            fps = 1.0 / dt
        else:
            s = np.clip(dt * 3., 0, 1)
            fps = fps * (1 - s) + (1.0 / dt) * s
        setText('%0.2f fps' % fps)
        start = time()
        app.processEvents()
        print(time() - start)

    timer.timeout.connect(update)
    timer.start(0)

    if __name__ == '__main__':
        import sys

        if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
            QtGui.QApplication.instance().exec_()

bit = np.arange(0, 257, 1)/256
colmap = np.array(255 * plt.cm.nipy_spectral(bit), dtype=np.ubyte)
main()