SLOW GPS

usalo mas , segun mi experiencia y no se cual es el motivo cuanto mas lo usas mas rapido es , en mi caso me tarda unos 15 segundos , aunque como dices en ocasiones tarda mas .

creo que el chip de Sony aun no esta bien optimizado

It might not have the latest CPE data loaded on the watch, or, worst case, not have a CPE file installed.

This should technically update with a Garmin Connect sync, but try connect it to a PC and sync the watch with Garmin Express if you haven't

CPE files are used by the watch to predict where the GPS satellites are located, and with them missing or expired, GPS location could take a very long time.

So give it a shot.

EDIT, I've also heard that a forced WIFI sync on Garmin devices can sync the CPE/CPO data, but not sure about the VA4

I suspect the VA4 / VA4S has inferior GPS antenna reception compared to most other Garmin watches. Some say it is because of the metal ring around the display. My VA4S is also sometimes slower than expected to get the signal, and is less accurate than other watches and my mobile phone when logging a GPS trace. 

I've not had an issue with acquiring GPS signal... 5-10 seconds max.

Keep in mind that both Garmin Connect and Other websites like Strava don't plot your GPS points exactly as they were recorded... in order to minimise processing, there is a "smart" plot that goes on that can sometime look unrepresentative of the original data. Also, Smart data recording on the watch isn't always perfect either.

If you want to determine an accurate view of what your watch recorded, export the GPX file from Connect and view it on Google Earth, or Garmin Base Camp. On these platforms every recorded GPS plot will be shown, and from here you can determine if accuracy is an issue.

Proper CPE or satellite ephemeris data is important for your watch or other GPS unit to have, otherwise it will take a long time to acquire a sufficient number of satellites in good enough time. GPS signal will be good with already 3 satellite connections, but that isn't accurate enough to even get proper elevation data. And there is no way that I know of to show how many satellites a watch is connected to at any given time, so it is important to have this CPE data on the watch.

Garmin has had issues with devices not syncing this file properly, or it has disappeared off the device, or it may be consistently "expired"... that needs to be established. I find that syncing with Garmin Express on a computer is most often the best choice to get this data updated properly...