I wouldn't have thought 700 ft would make any noticeable difference. Jet A is pretty much the same anywhere (although some has FSII and some does not).

Is there a temperature difference between the places you are flying.

I would guess that, either you are getting used to the plane as you say, or you have a different problem. The other thing that I have found affects the feeling of speed is the flying site. If the site is wide open with no restrictions then the model feels slower than flying somewhere where the pattern needs to be kept quite tight.