You know how BSD advocacy folks like to tell you they "don't like politics"? It's kind of like the story in the Onion about that guy who keeps telling people he doesn't own a television and how much more fulfilling his life is, even when no one asked. BSD advocacy folks are _just as political_ as the GPL crowd. The reason to use GCC isn't performance, it's the only free compiler that supports a multitude of target architectures. And that's very very useful. Dropping utility over licensing kind of smacks of the thing GNU is accused of when BSD advocacy folks get all snooty about technical superiority.

The kernel developers don't seem to agree on the right way to fix this, whether at the kernel level or in userspace. However, it may affect the performance of the kernel if it's done in kernelspace, and it is impractical to have everyone rewrite their userland software, as someone else pointed out. The "patch" which is available for FreeBSD to fix this problem only disables hyperthreading and does not provide a real fix.