With most games in development, optimization is one of the last steps. They try to get the major programming done before cleaning up the code. I imagine the game will be running smoother by the final release. Then again, RCT 3 still runs pretty sluggish on my fairly modern PC . . .
I think it is encouraging that they did a beta test for this game. Give the developers credit for trying a new system for a coaster builder, and one that I think has potential. Hopefully they really try to apply this feedback into cleaning up the builder to make a better experience. I don't know that there will be major changes before the official release, but if they are serious enough to completely change course midway through the development, hopefully they will stay with the ship and make changes until it's right.