python - Unresponsive MessageBar in QGIS 3

I created a little plugin to geocode addresses using the HERE API and QGIS 3.

Especially in batch mode, I can see that the plugin is iterating over my features in a table and my messageBar progress is working as expected.

After a few seconds, QGIS gets unresponsive and the progressbar stops. This happens in a non-reproducible way.

The relevant code section is:

    progressMessageBar = iface.messageBar().createMessage("Looping through " + str(layer.featureCount()) +" records ...")
    progress = QProgressBar()
    progress.setMaximum(layer.featureCount())
    progress.setAlignment(Qt.AlignLeft|Qt.AlignVCenter)

    progressMessageBar.layout().addWidget(progress)
    iface.messageBar().pushWidget(progressMessageBar, level=1)
    for id in range(0, layer.featureCount()-1):
        urlPart=""
        oldAddress=""
        for key in addressLists.keys():
            if key != "oldIds":
                urlPart+="&" + key +  "=" + addressLists[key][id]
                oldAddress += addressLists[key][id] + ","
        url = "https://geocoder.api.here.com/6.2/geocode.json?app_id=" + appId + "&app_code=" + appCode + urlPart

        r = requests.get(url)
        if r.status_code == 200:
            if len(json.loads(r.text)["Response"]["View"])>0:
            #as the response may hold more than one result we only use the best one:
                responseAddress = json.loads(r.text)["Response"]["View"][0]["Result"][0]
                geocodeResponse = self.convertGeocodeResponse(responseAddress)
                lat = responseAddress["Location"]["DisplayPosition"]["Latitude"]
                lng = responseAddress["Location"]["DisplayPosition"]["Longitude"]
                ResultFet = QgsFeature()
                ResultFet.setGeometry(QgsGeometry.fromPointXY(QgsPointXY(lng,lat)))

                ResultFet.setAttributes([
                    addressLists["oldIds"][id],
                    etc...

                ])
                ResultFeatureList.append(ResultFet)
        progress.setValue(id)
        iface.mainWindow().repaint()
    pr.addFeatures(ResultFeatureList)
    iface.messageBar().clearWidgets()

Here is the behaviour in a gif:

The main functionality below is embedded in a function which is connected with the button. The connection is defined in the main run function of the plugin:

    def run(self):
        self.dlg.show()
        self.dlg.LayerSelect_2.currentIndexChanged.connect(self.searchFieldsPopulate)
        self.dlg.batchGeocodeFieldsButton.clicked.connect(self.batchGeocodeFields)
        result = self.dlg.exec_()

        if result:

            pass

UPDATE When adding a short sleep prior and after progressbar update the progress bar seems to update better and the system is responding and not showing any unresponsive messages in the plugin/QGIS application.

    time.sleep(0.2)
    progress.setValue(id)
    time.sleep(0.2)