in reply to
Re^3: Standard way to convert timezone in multithreaded script
in thread Standard way to convert timezone in multithreaded script
However, n=1 (recommended setting) only pegs one core.
Yes, of course. A single thread will only execute on one core. Which core that is may change (it's up to the OS), but it won't run on more than one core simultaneously. Multiple threads will.
(I guess you already know this, just saying it explicitly in case someone reads all of this and is under the impression that simply saying "use threads;" will make a program run concurrently on several CPUs. That would be magic, not concurrency :-)