13" tbMBP Processor

By "base configuration" do you mean the non-TB MBP 13? This base configuration is an i5-6360U that turbos up to 3.1GHz, so I think you are asking how this compares to the TB model with i5-6267U that turbos up to 3.3GHz.

There are a few comparisons out there, but most show about 5-10% better CPU performance for the TB model and about 10-25% GPU peformance increases depending on the test. If you are not using the GPU extensively, then the difference may not even be noticeable.

The thermal throttling (see ArsTechnica review) apparently only occurs with GPU load, and both machines can sit at their maximum turbo speeds for at least 30 minutes when running CPU-only loads.

I don't think there is a case where the more powerful 28W CPU would end up throttling *more* than 15W. It has a higher TDP so can get hotter before it needs to throttle, and the twin fans should ensure that it keeps cool enough to keep within the TDP for longer.

If you disregard the touch bar, extra ports, faster RAM etc. and you mostly do activities that do not depend on the iGPU, then the processor upgrade in the TB version does not amount to a great deal. If you find you need the extra GPU grunt, then you might also be better off just going for the 15" version.

For me, the nTB version is the better deal; YMMV!

 

Ah, I see what you meant now!

Personally, I think the Apple CPU upgrades are overpriced. Have a look at ark.intel.com. The 2.9GHz and 3.1GHz CPUs you are asking about are the same list price ($304), yet Apple will charge you $100 for the faster CPU! There isn't a price shown for the i7-6287U, but you can bet it's not $300 more expensive.

The specs of the 2.9GHz and 3.1GHz i5s seem to be identical apart from the clock-speed. I'm not sure the c. 7% speed increase will really be noticeable in most tasks except very long-running processes like video encoding.

I bought a CPU upgrade once before (i7 in an MBA), and really don't think it was worth it - it reduced battery life, and I doubt I would have noticed the difference.

 

It makes no difference really they are all dual core CPU's clocked very fast unless you are always maxing it out you'll never notice.