How do you know the game is CPU intensive? The fact that it runs slow doesn't necessarily mean the CPU is at high use. Actually I am sure the 68000 emulation is the least of the speed taxing problems when emulating an Amiga.
I am sad all developers jumped on that Pandora thing. Uae4all on my Caanoo, albeit a ruhed job, manages to run a lot of games at full speed and it's pretty impressive. If anyone had done a proper port, it would have been awesome.