Haven't been able to find a clear answer on this. I'm interested in 75-500Hz bandwidth. It's for a tuner(android app) so i want a pretty quick response time.
Is it worth the computational time to high pass the signal?
The computational overhead of a band-pass or high-pass (DC blocking) filter on a processor capable of pseudo-real-time musical pitch detection and estimation accurate enough for tuning (+-1 cent?) is probably a small fraction of a percent.
Yes, it is. If you pickup signals with a microphone you will often see enormous amounts of low frequency signals (air condition, HVAC, traffic, wind, etc.). Even in quiet rooms there tends to be a lot of very low frequency noise.
This noise can dominate the time domain waveform and reducing it can often make your pitch detector more reliable and/or allows for a cheaper or more efficient algorithm.