Both the Smarthome/INSTEON profile and the Foscam profile will work with the INSTEON cameras.
Based on your description of the slow to connect, but fast video once synced, when I've seen this it's due to a mangled RTSP stream from the camera. That could happen for a couple of reasons:
1. The camera is on a weak Wi-Fi connection and doesn't have a good solid connection. To test, move the camera to a wired connection and try again.
2. The iOS device is on a weak connection. To test, make sure that the iOS device is in the same room as the Wi-Fi router.
3. The camera is setup to send a very large or high quality image stream. To test, reduce the size of the stream down in the camera's settings.
4. The camera really might have gone bad and isn't able to send proper RTSP data any more.