"RISC" isn't a single architecture, it's a philosophy for designing architectures. The "RISC" Apple was using before x86 was called PowerPC, and it was designed mostly by IBM. It was also a horrible piece of overheating garbage that I'm still honestly surprised wound up in the Xbox 360 and PlayStation 3. The "RISC" Apple is using now, ARM, is a far more practical architecture that Apple has already beat Intel with in single-thread perf... at a lower clock rate, with strict power limits. Letting the A13 stretch it's legs with wall power and a big heatsink would completely crush Intel and x86 in every benchmark except multi-threading.
User-perceived latency has little to do with the clock rate of a processor, though. What you need is:
1. Immediate feedback upon user input
2. Progress animations that move, even if progress is indeterminate
3. High frame rates on your animations
4. No frame stutter or torn frames
Out of the four, low clock rate will mainly impact frame rates and pacing, but that can still be mitigated by using what you have as efficiently as possible.