The cycling science for a while had been continually increasing the cadence that was thought to be ideal for pedaling efficiency. In the early nineties it was at about 90 rpm and then it got pushed up to something like 115 in the Armstrong era. Lance himself may have had something to do with this since he preferred a faster cadence. Regardless, it has been almost universally agreed on that a cadence slower than 80 rpm is inefficient. As a default you should probably shoot for something much higher at around 100 rpm unless you've actually done wattage tests on a stationary to show that you are personally more efficient at a slower rpm. 48/16 at 100 rpm would mean that you are averaging about 23 mph. This is a doable speed for 20 mile rides but would generally be considered quite fast. Nobody I follow on Strava is usually doing that kind of speed and 18 or 19 mph would usually be on the faster side. 48/19 at 100 rpm is still almost a 20 mph average. At 80 rpm that would be almost 16 mph.
If your goal is to ride efficiently (and faster overall) then trying a larger sprocket makes sense.
Even though there has been a downward trend in the recommendations for rpms in the last couple years, it is still the case that almost every cyclist you see on the road has a cadence that is slower than ideal.