By the info I could gather, cemu 1.7.3 can run the game without Single Core Interpreter selected, therefore the fps is better.
On 1.7.3b, Single Core Interpreter must be enabled, else the game will crash after the "Open Your Eyes" + yellow light screen. Problem is, with this thing turned on, performance dies.
The work around for this should be pretty easy by playing the beginning on Wii U and dumping the save. Unless it crashes also later.