The UE40F6510SB has one of the faster high frequency rates (400 hertz) amongst medium display diagonal TVs of this age. The slowest high frequency rate of medium display diagonal TVs that have been available for a comparable time to this TV is 50Hz and the fastest is 1,600Hz.
There are a number of other 400Hz refresh rate TVs currently available which you might want to consider including the 47LA691, or the 42LM670S both from LG which and both of have better reviews.
TVs with a faster high frequency rate that might be worth looking at include the Panasonic TX-L42ET60E (600Hz).
What does "high frequency rate" mean?