How much CPU the real-time stretching of a stereo stream (let’s say 44.1k) will take using your library? Do you think 5 is possible?

The SuperpoweredTimeStretching class has been designed to be extremely CPU efficient. 16 instances are possible on the iPad 2 with the buffer size of 512, on a single thread, together with other effects, mixing, etc. The same 16 instances on the first iPad Air (64-bit) will use no more than 40% of the available time of the buffer size 128. 5 instances can easily be handled by the first iPad.