[Scenario]

y_commands has been proven to be faster than ZCMD if you have OVER 100 commands in your game mode- but it also offers some neat features so you could always give that a look. The performance difference is minimal so you could always use that over ZCMD and still be fine. Sscanf is still a fantastic thing to use. BlueG has abandon his plugin, but Pain123 has taken over the development of it and it's far better now. However, you'll want to be using threaded queries if you plan to use any version after R6 (you should be using R31 with threaded queries though).

As far as new features, I would check the last couple of SA:MP updates in the "News and Announcements" board or whatever. We've had quite a few enhancements within the past few years.

Have fun!