'Had the same on the Mac Demo on my Core2Duo MacBook (2,13 GHz, 8 GB RAM, SSD Drive, NVIDIA GeForce 9400M 256 MB ), but in all NPC Duels - the targeting for the attacks was really lagging, too, and had to throw a few potions to get the last couple of steps to not "finish" first / lose.
So, maybe would be nice to get an idea about your system config (processor, RAM-amount and GPU at least) to see if it's some older hardware issue or maybe a code processing problem.