Same issue here. Once I turn off the smart guides, things speed up. But, I noticed that when I'm plugged in to my 2nd screen things slow down as well and that once unplugged, things run a bit smoother. I am however on the Yosemite Developer Preview.
My specs are,
MacBook Pro (Retina, 15-inch, Early 2013)
Processor: 2.7 GHz Intel Core i7
Memory: 16 GB 1600 MHz DDR3
Graphics: NVIDIA GeForce GT 650M 1024 MB
