A Vaio P4? Are you sure it's not a P4m? The P4m does not support HyperThreading. It's a BIOS option. It's not two virtual processors running at 1.25 GHz. That is not even vaguely close to what's actually going on. The idea is that while a lot of people refer to the P4 as being "narrow and fast" (mostly this is how the clueless compare the G4 and the P4), the fact is that the P4 has a lot of execution resources. It has in fact nearly as many functional units as teh G4. HT is a method that allows the processor to schedule instructions with greater flexibility when using multiple threads, so that it can find more ways to feed instructions into all of those functional units. In other words, HT is one way that Intel has been working to improve the "IPC" of the P4. Initially, there were some issues with HT and cache aliasing that hampered single-threaded performance (which is why it was initially limited to the Xeon family, where single- threaded performance is not much of an issue since the Xeon's primary market is servers). You're probably running into the P4's biggest weakness: it needs memory bandwidth. Most laptops using P4m's don't have enough to keep it fed, so they can't showcase anywhere near the performance of a desktop P4 with a Springdale or Canterwood chipset, even though they are based on the same core. Also, since HT increases the amount of work the processor is doing, it also makes it hotter. It will not be supported in P4m's until early next year (Prescott variant) according to Intel's roadmaps.