My understanding is the main difference between i5 and i7 is support for hyperthreading. i7 has it, most i5’s dont. This actually isn’t a bad thing for Cantabile since usually you don’t want to use hyperthreading.
The idea behind hyper-threading is that since each processor core is highly pipe-lined and has multiple execution units by allowing it to execute multiple threads at the same time each thread can (hopefully) use different parts of the pipeline and get more done.
The problem with real-time stuff is that the biggest bottleneck tends to be floating point math - and I don’t believe any current cpu has multiple floating point units in a single core. So you just end up with multiple threads fighting over the floating point math unit - and it actually makes things worse.
I haven’t actually tested this for quite a while now and things may be better in the latest processors, but at the time, enabling hyper-threading and dialing up the thread count to more than the number of physical cores was a disaster - causing it to run much slower.
This is why Cantabile’s audio engine options recommends running at the number of physical cores - not the number of virtual cores.