I've always used GPS alone on my old Nexus One, and today I ran a test, with both devices freshly rebooted and in the same location. The N1 took 28 seconds to get a fix. The Xperia Z2 took 2 minutes and 16 seconds. This is with the latest firmware, .402. (With the previous one, FW:17.1.A.2.55, GPS worked a little faster, but still took about a minute or so, in plain outdoors with no trees or tall buildings around).