In case you were wondering if the popularity of Google Earth is straining Google’s servers (and some have wondered), you can rest assured:
In a support forum post, PenguinOpus of the Google Earth team mentions:
Google Earth servers currently have enough capacity that no rate-limiting has occurred in several months. Your performance will be controlled by your own ISP’s throughput and your latency to our servers. Ping kh.google.com. <100msec, good. >200msec, not-so-good.
(Here in Sweden my average ping response is 22.6msec (!))