Hi. I am experiencing exactly the same issue - once ICAO data are shown on map, the response of the program is 2-5 seconds. ZOOM levels settings have no effect on this, as these settings only specify at which ZOOM level the ICAO data are to be shown, and once they are shown, computer gets very laggy. It also affects other programs, scrolling in mozilla is stuttering for instance. CPU utilization is around 20-50% on Core2Duo 2GHz, I am using networked config with IVAP and ASN also running. I never had this problem with V2 version. Yes, it could get laggy too, but it was still usable, but this is affecting the whole computer, not just planG.

I had just the same now when I tried out the new V3 version. There were 5 updates for the .NET FW 4 and each time I ran the update without any error, the next time I scanned for updates these 5 appeared again.
Simple solution - uninstall all NET 4 entries from the control panel-programs, then download full .NET 4 installer ( http://www.microsoft.com/en-us/download/details.aspx?id=17718 ), install and then the updates should work without appearing again.