A non-technical user of this hypothetical iOS app won’t be able to tell if the author had to do some clever algorithmic hacks to get an acceptable level of perf

A non-technical user of this hypothetical iOS app won’t be able to tell if the author had to do some clever algorithmic hacks to get an acceptable level of performance, or if s/he spent a whole day figuring out how to work around an undocumented bug in some versions of iOS, or if the whole program is really a mountain of kludges that will cause endless pain to the next coder who tries to add a feature to it.