What is your latency? Can you move data closer to where db is (cloud)? Did you change isolation level? Or recovery model? Did you try bcp? Any indexes you have in table should be deleted?

Belgrade, Serbia got you covered: https://www.openstreetmap.org/way/39596307 (we were once socialist country, but more and more streets are losing their original names nowadays:(

If you are looking to get data on your route (speed, distance), regular gps will do, errors are not high, as these error cancel each other usually. If you plan mapping for OSM - also really not worth it, as OSM is generally not more precise than 2-5m. I have dual-frequency phone and I am not impressed (accuracy is bit better, but I didn’t have wow effect). If I choose again, I would optimize my purchase for battery life (far more important in nature:D)