Why are you using filtfilt (which applies the filter twice, forward/backward) with a symmetric FIR filter (which is linear phase by itself and doesn't need forward-backward filtering to achieve linear phase)?
filtfilt() takes about 20 times as long as doing regular forward filtering with filter().
Avoid using filtfilt unless there is a pressing reason to do so (i.e. linear phase required when the filter itself is not linear phase). Also, keep in mind that filtfilt applies the filter twice and the frequency response will not correspond to what you see with freqz().
Also, be aware that filtfilt is, in essence, acausal. The input sample value at t0 will affect the output sample value at t1<t0, i.e. the present will be affected by the future.
