The cheating was caught by the new AnTuTu Benchmark X app. This version of the benchmarking app is coded in such a manner as to catch cheaters. As described on the Play Store:
A special edition of AnTuTu Benchmark to prevent fraud and cheating!The standard version of the benchmark is here.
The X editor for the Ainol & Ramos device!!
AnTuTu Benchmark X Edition is free benchmarking app that helps users to know deeper to their Android devices, without fraud and cheating!
Bemchmariked with the standard version, the HTC One (M8) managed an amazing 38,815 score, which is miles ahead of the Galaxy S5’s 34,898 score. When the X version of the app is used, the HTC One M8 slows to a snail-like 27,171 while (strangely) the GS5 rises to 35,357.
When asked about the results, HTC crowed it was a feature.
Thanks for your email about the HTC One (M8). Benchmarking tests look to determine maximum performance of the CPU and GPU and, similar to the engine in a high-performance sports car, our engineers optimize in certain scenarios to produce the best possible performance. If someone would like to get around this benchmarking optimization there are ways to do so, but we think most often this will not be the case.The new High Performance Mode, HTC added, was not yet available on U.S. devices, but will come to them shortly via a software update.
For those with a need for speed, we've provided a simple way to unleash this power by introducing a new High Performance Mode in the developer settings that can be enabled and disabled manually. The HTC One (M8) is optimized to provide the best balance of performance and battery life, but we believe in offering customer choice, as there may be times when the desire for performance outweighs the need for battery longevity.
It's not hard to understand why companies do this. Reportedly, only Apple doesn't include such tomfoolery on its devices.