PC games and emulated games are not comparable. Your CPU isn't that great to begin with running at 1.7GHz. It seems like you have enough "juice" to run the game alone at playable speeds. If you introduce another program that is also trying to grab CPU cycles while Dolphin is trying to run the game at speed, things are going to slowdown at times.
Asus Laptop: K53TA
OS: Windows 7 Home Premium, 64-Bit - SP1
CPU: AMD Llano A6-3400M, Quad-Core, 1.4GHz-2.6GHz (Overclocked)
GPU: AMD Radeon HD6650M, 1GB GDDR3 (Catalyst 13.1)
RAM: Samsung 4GB DDR3-1333
OS: Windows 7 Home Premium, 64-Bit - SP1
CPU: AMD Llano A6-3400M, Quad-Core, 1.4GHz-2.6GHz (Overclocked)
GPU: AMD Radeon HD6650M, 1GB GDDR3 (Catalyst 13.1)
RAM: Samsung 4GB DDR3-1333