Well, you asked, so let's stir up the pot a bit...
Improvements in the last 10+ years are mostly higher cost.
I shoot an old Browning wood frame compound from the 90s. It is longer than the newer ones and also lighter. I prefer the longer bows since I still shoot fingers, rather than a release. Shorter bows make for a more acute angle from the knocking point to the ends of the bows. When shooting fingers, this causes an unacceptable pinch. The expectation for short bows is that everyone will be using a mechanical release.
Also the newer bows have a higher percentage of "let off" at full draw, some as high as 75%. The downside here is a much heavier pull though the draw weight about 1/2 way into draw. Almost like drawing a crossbow. A theoretical advantage of the shorter bows is that the "push" of the string against the arrow lasts longer and could give a greater acceleration and faster arrow speed. However the difference is only about 10-15% over the longer, older compounds. Plenty of deer have been killed with recurves and longbows at 1/2 the arrow speed of the compounds.
FWIW, I believe the shorter compounds are inherently less accurate than the longer bows. Notice that the target shooters all shoot longer bows, with lesser let-off. Likely this gives a more consistent release and acceleration imparted to the arrow. The biggest advance in the last 25 years, in my opinion has been carbon fiber shafts, about 1/2 the weight of the aluminum shafts. Higher speed arrows, flatter trajectory, same penetration. And the carbon shafts don't bend.