Google, response time

As it looks, sending the same query several times results in an quicker answer:

Searching for "hello":
* First time: ~30 ms
* Next time: 5-10 ms

OMC-Cs: Caching looks probable, perhaps also only due to disk / memory caches?

Rough estimations about Response Time + Bandwidth:
* Disk performance (see http://www.storagereview.com/): ~9ms / 50 MB/s
* Network performance (1 Gigabit Link): ~0.3 ms / 120 MB/s
* RAM performance (http://arstechnica.com/paedia/storage.html): ~50 ns / 5 GB/s
* CPU performance: ???