GCC celebrates 25 years with the 4.7.0 release

I frankly doubt you'd see enormous improvements in non-pathological benchmarks anyway, because the kernel is not the predominant consumer of CPU time in most benchmarks, and LTO will do nothing to improve locality of reference or any of the heaps of algorithmic things which a kernel has to deal with and which really do take time. You'd probably see an improvement from reduction in icache pressure though, but I have no idea how big it might be. Probably minimal, but one can hope.

As always, the numbers will tell.