http://www.tomshardware.com/cpu/20050603/index.html#overall_performanceQuote from dcraig:
In fact many Java applications are multithreaded and TWS certainly is - just look in the log file. The only catch is that all updates to the screen in Java/Swing applications such as TWS are (or should be) done by a single thread - the AWT thread. If this one thread is consuming most of the CPU cycles used by the application then dual cores or multiple CPUs won't help much for that application.
System performance is a complex issue, but if you are running more than one application at a time eg TWS and charting software, browser etc, I think you will be better off with the cheapest dual core Athlon than the most expensive single core. The machine is likely to feel a little snappier too.
Unlike hyperthreading which was always a bit of a marketing ploy by Intel, multiprocessor (SMP) machines have been around for many years. The technology is well understood and acknowledged to yield very significant performance improvements. Dual core is just mutiprocessor where the multiple processors (two in this case) are built on the same chip.
Intel seems to be doing great in multitasking as of late!

