Where'd you hear that?Quote from maxpi:
...The multi-processor rule of thumb is that a quadrupling of processors will double your speed...
Depending on your job mix, benchmarks typically show relative performance like this:
1 processor = 1x
2 processors = 1.5-1.85x
3 processors = 2.25-2.75x
4 processors = 3-3.7x
This of course assumes you are actually running several things at once or one multi-threaded heavy CPU app. Running a single, single threaded app even on an 8-way box doesn't produce any incremental performance at all. But if you're running at least one multi-threaded or 2+ single threaded CPU consumers, you'd see more than a minor throughput boost from a dual (by "running" I mean they're really executing most of the time, not just active apps that you flip back and forth between).
However, most traders aren't typically CPU bound, so they're better off putting the cash into a bigger memory footprint or a faster single processor machine (assuming they really need the extra CPU).