I thought of another way you can fall back to some faster iPhone 4 performance along with the other two suggestions. In the file PocketsphinxRunConfig.h there is this sequence:
#if __LP64__ #define kBEAM @"1e-96" // -beam Beam width applied to every frame in Viterbi search (smaller values mean wider beam), defaults to 1e-48 #else #define kBEAM @"1e-66" // -beam Beam width applied to every frame in Viterbi search (smaller values mean wider beam), defaults to 1e-48 #endif
You can set the value 1e-66 to a larger value such as 1e-48 for faster searches on older devices. I would leave it as-is for the devices that are already performing satisfactorily.