PickerView Lags when there are many values

I've added a list of strings of numbers  from 10 to 500. When I'm scrolling up to 200th string UI is very laggy. At 275th , picker is almost not usable due to lag.  I found this issue when testing on an iPhone 5 (iOS 7) . On Simulator I had to scroll upto 350th+ to experience the lag. Is this happening because not dequeuing and reusing items?
