Thanks for the reply Janch. The GPS fix is quite fast, the signal never lost even while going under short tunnels and I've never seen "Looking for GPS signal" message, altitude info is also very correct. Another software -Mireo Don't Panic- is better regarding this delay issue. So, I don't think it is related to antenna. Somehow primo is a little bit late on GPS signal processing. I use same com port (1) and baud rate (38400) in both software.