That's really hard to answer. Every year, bike makers come out with claims that this year's model is N% more aerodynamic than last year's, etc. Although they don't always give hard specs on CdA.
Also, we don't know what shape your bike is in. A new bike would have a new drivetrain, and your current one might have a lot of wear, which would make it somewhat less efficient. A new one would have whatever tires are stock, but presumably you've gotten new tires since you bought this bike. Maybe those are top-quality racing tires with even lower rolling resistance than the hypothetical new bike, maybe they're bricks.
Also also, a lot of the improvements that go into bikes from year to year can't be measured in a one-hour time trial. For example, there's been an overwhelming shift toward disk brakes, which offer better stopping power in the rain and better modulation in all conditions. There's also been a trend toward wider tires, which reduce rolling resistance and increase comfort. Your current bike probably can't fit the 35-mm tires that many modern road bikes could. A new bike would probably give you another gear or two in back, so you could get a wider gear range with the same ratio spacing.
Weight alone makes surprisingly little difference in performance unless you're on a steep climb, and even then, it needs to be a considerable amount of weight—say, 1 kg—to make a meaningful difference to an amateur cyclist.
So: your current bike isn't bad. If you put top-quality tires on it, a high-quality chain, and a new cassette, and made sure everything was in good tune, a new bike wouldn't offer much advantage in terms of plain speed, but a new bike might offer other quality-of-life improvements that would make it worthwhile.