Thanks for clarifying the extra memory controller, that's helpful too.
No. The single core CPU performance has zero relation to memory bandwidth.[0] i.e You do not gain or loss any performance going from M1 Pro 10 Core with ~200GB/s Memory bandwidth to M1 Max 10 Core with ~400GB/s bandwidth. The additional memory bandwidth are there only to support GPU performance.
The reason why CPU performance is fast is slightly complicated. But to over-simplify it to two point, Apple has access to all the common code path on their platform and can optimise of it. e.g NSObject release is 5 times faster than on x86. Second being Apple managed to do something the whole industry thought ( at the time ) was impossible, having a wide decode and kept them well fed. You can read more about it here [1] on HN.
> what it'll look like in a year or so with the M2/M2Pro/M2MAX then.
You can take a look at [2], which is a chart from Nuvia, started by ex-Apple CPU architects. Given the amount of lead time in CPU design ( 3-4 years ), you can pretty much bet Apple will follow the path as shown by Nuvia to reach a Geekbench Score of 2000 within next 2-3 years.
Hope this answer your questions.
[0] CPU Performance is always latency sensitive. Hence the amount of cache matter much more than memory bandwidth. And Apple's SoC has always had large amount of cache compared to rest of the industry, even when it is a Smartphone SoC compared to Desktop part.
[1] https://news.ycombinator.com/item?id=25257932
[2] https://www.anandtech.com/show/15967/nuvia-phoenix-targets-5...