Actually there is an easy way to find out (not 100% tough):
– Turn on the caching on the search caching options panel
– Try to search for any phrase once. Wait a few seconds, then search again for the exact same phrase. Do this a couple of times. After the first search, the second, third, fourth etc… searches for the same phrase should be a lot faster, I mean super fast, like under half second. If it’s not that fast, then there is definitely something else involved.