> In other words [because the access sequence is just 10 instructions], memory will be the bottleneck, not the instructions to calculate where an index is.

Ha, that is wishful thinking. If you do this in a tight loop in which everything is in the L1 cache, the instructions hurt!

"Memory bandwidth is the bottleneck" reasoning applies when you access bulk data without localized repetition.

Those 10 instructions are for one access, not for a tight loop. A tight loop could be done with a much more complex macro that iterates separately in each segment, amortizing the overhead.