Creating own marker with iconView on Google Maps - swift

Question

I created my own marker with iconView for showing my own position. As you can see it is the green one. But every time I move the screen it is reloading my green view and it seems lagging. I don't have the same problem with the other marker shown, which are simple png.
How can I solve that? I can solve that problem by removing the line mapView.clear() But the result is that every loaded marker don't go away if I zoom out. So the map gets more and more crowded.
func mapView(_ mapView: GMSMapView, didChange position: GMSCameraPosition) {
mapView.clear()
let fullCordinate = "\(mapView.camera.target.latitude),\(mapView.camera.target.longitude)"
networkGoogleApiConnect.fetchPoi(geoCordinate: fullCordinate)
networkGoogleApi.testVariable.forEach {
let marker1 = GMSMarker()
marker1.position = CLLocationCoordinate2D(latitude: $0.position.lat, longitude: $0.position.lng)
marker1.title = $0.title
marker1.icon = UIImage(named: "house")
var dict = [String:String]()
dict["id"] = $0.id
marker1.userData = dict
marker1.map = mapView
locationManager.stopUpdatingLocation()
}
locationManager.delegate=self
let neuLongitudeEigenerStandort = locationManager.location!.coordinate.longitude
let neuLatitudeEigenerStandort = locationManager.location!.coordinate.latitude
let fullCordinateEigenerStandort = "\(neuLatitudeEigenerStandort),\(neuLongitudeEigenerStandort)"
let ownMarker = GMSMarker()
ownMarker.iconView = UIView(frame: CGRect(x: 0, y: 0, width: 20, height: 20))
ownMarker.iconView?.backgroundColor = .green
ownMarker.position = CLLocationCoordinate2D(latitude: neuLatitudeEigenerStandort, longitude: neuLongitudeEigenerStandort)
ownMarker.title = "Eigene Position"
ownMarker.snippet = "GPS"
ownMarker.icon = GMSMarker.markerImage(with: .blue)
ownMarker.map = mapView
}