My question to you experts is whether there is a huge difference between i5 and i7 processors?
I can share my experience with a dual core i5 vs quad core i7.
I have a mid 2014 13" macbook pro with 2.6 GHz Intel Core i5 and 16gb ram, 250gb SSD.
Using Capture One To process out around 3000 22 megapixel CR2 files to jpgs takes about 8 - 10 hours.
Doing the same process on an iMac with 16GB ram and an i7 processor takes 2-3 hours.
Granted that might be a bit of an apples to oranges comparison, but watching the activity monitors on both machines I always found the CPU working overtime and there was RAM to spare.
Next macbook I buy I will be upgrading to the faster CPU as that seems to be the bottleneck.