Scrypt (Litecoin) memory / performance tradeoff For Litecoin, if memory size is increased in processing the Scrypt algorithm, for example to 384 kB instead of 128 kB (and assuming likewise an L2 cache size of 384 kB), would the typical CPU architecture (x86, PPC, etc) be likely to see a corresponding increase in performance?  And if increased memory size were used, would mining output remain 100% compatible with Litecoin (I believe the answer is yes, but also I note that almost all GPU miners are using fixed Scrypt parameters for N, r, and p).

I realize that increasing BlockMix memory sizee is not typically done on GPU architectures, for various reasons.  Also as a note my objective is not profitable Litecoin x86 CPU mining -- I just want to be sure I understand the  memory/performance tradeoff.
For Litecoin, if memory size is increased in processing the Scrypt
  algorithm, for example to 384 kB instead of 128 kB (...), would the typical CPU
  architecture (...) be likely to see a corresponding increase
  in performance?


No, it works the opposite. If you increase memory, which is used by the scrypt to generate a single hash, the time it takes to generate it, in theory, will increase. The time may not increase if the processing unit can fully use its fastest cash in a single data transfer call. However, you need standardised hardware and you would want to deliberately adjust scrypt memory size for it. Which is inconvenient on a global users scale.

Moreover, it's not up to you, personally, to decide the memory size of scrypt. This is a universal agreement of all litecoin users, that memory size of the scrypt algorithm has to be N bytes. If you want to use something else, any transaction you issue will never gets validated by any other users.