I can tell you for sure there's a significant difference between the normal current code and v1.05 buffer. It's not input lag, or even slower (even though it sure does feel that way at first). Though, it's not a matter of speed at all. It's just that with the new buffer everything is tighter. So if you input something, there is a certain amount of frames you need to wait before you can input again. That's what it means to have a smaller *input buffer*. It doesn't sit and absorb a million inputs and go to the next thing. I can play the CC cab at my local arcade and it almost feels like PS2, but v1.05 is much different.
There is probably nothing wrong. Mash less.