Tasing this game is quite addicting, but also tedious in its places. My times for the first world are:
Green Hill 1: 0:24:25 - Some different jumps and faster loop
Green Hill 2: 0:13:07 - New setup for the zipping (my first zip in a Sonic game ever)
Green Hill 3: 0:30:45 - Time gained at the boss, in order to deliver the final blow as fast as possible your y-subpixel value, when landing on the platform, must be < 80
http://dehacked.2y.net/microstorage.php/info/1263748122/Sonic%20The%20Hedgehog%20%28W%29%20%28REV%2001%29%20Aglar_world1.gmv
Thanks to Sonikkustar for the his previous work that provided great help!
Apparently, it's random how the animals that you set free are jumping and I lost some time here. Would the priority be to beat the level as fast as possible or wait some frames before hitting the button to get the best randomness? I like the former best (even if it's not enough for gaining an extra clock-second) as it's more consistent with the in-game time goal for the run.