Where'd you hear that? 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).
ArchAngel is correct. You can get a decent performance improvement on even two processors IF you are using application software that is written to take advantage of multiple processors. In our organization traders workstations DONT qualify for this - as previously stated NOT CPU bound - and we use this only on servers: The servers DO run mutiprocessor aware applications which are written specifically to take advantage of the extra processors. These are things like special purpose math computations on large datasets and things like large relational database systems. Things like MS SQL Server and Oracle will perform better on multiple processors if they are working on complicated queries and processing operations on large datasets. look before you leap and know what you need: many many people and organizations overbuy without knowing what their actual requirements are ......