I see the dilemma and I was probably a bit too quick to criticize Locus.
I can admit Locus is excused when displaying tracks recorded by another app like MyTracks, since MyTracks obviously store points unfiltered and applies smoothing when analyzing the track afterwards. I looked at a track recorded by Locus during a flight, and it was actually very smooth. Two Locus bike tracks do have some altitude noise that will add more uphill/downhill meters than actually is the case. When I looked at Locus tracks of two walking trips, that charts were quite noisy. So it seems that the lower the speed, the more incorrectly the smoothing works.
When to do smoothing - during recording or as post processing? Well, we know that the raw data are not correct anyway, so why store it unfiltered? If the smoothing algorithm is fixed and not user selectable or speed dependent, then storing raw data and doing post processing should work fine too. But then the smoothing should be applied also when exporting tracks, such that the apps using those data, get meaningful data (my original example with MyTracks show how bad this can turn out when doing it the MyTracks way). If however the smoothing level were user selectable, then the smoothing has to be done during recording I think, otherwise you would need to change the smoothing level from track to track depending upon what kind of trip it was (flying, sailing, running, ..).
I see the challenge of how strong the smoothing should be: too weak will pass through too much altitude noise and hence add too much to uphill/downhill, and too strong will filter out some real up and downs in a rough terrain. So may be the smoothing algorithm Locus is using today during recording is the best compromise after all. Since Locus is supporting display of MyTracks recorded tracks, may be the same Locus smoothing algorithm should be applied before displaying those charts and statistics.
Regarding my phone hang problems with Locus, yes they remain. I even tried more things yesterday, but nothing helped. Locus crashed and killed the phone dead twice during the same 1 1/2 hour trip. But I also can be lucky once in a while and record a trip without issues.