Impressive, but if the goal is for BSD to have a faster grep then clearly the solution is to use GNU grep instead of rolling their own redundant and inferior clone.
You can release some software that contains both GNU GPL and BSD-licensed code, and it will be legal to distribute as long as you follow the rules of both licenses; as the rules of these licenses do not conflict, there's no legal problem.
This is what most people mean when they say two FOSS licenses are "compatible."
