gistfile1.txt

from qgis.gui import *

othermap = QgsMapCanvasMap(iface.mapCanvas())
othermap.setZValue(-9.0)

settings = QgsMapSettings(iface.mapCanvas().mapSettings())

def updatemap():
    global job
    global settings
    othermap.setContent(job.renderedImage(), settings.visibleExtent())
    
def redrawmap():
    global job
    global settings
    settings = QgsMapSettings(iface.mapCanvas().mapSettings())
    settings.setLayers([iface.activeLayer().id()])
    job = QgsMapRendererParallelJob(settings)
    job.finished.connect(updatemap)
    job.start()
    
iface.mapCanvas().extentsChanged.connect(redrawmap)
redrawmap()