There would be a performance hit, but that is likely to be insignificant. Apparently the stack check code touches every stack page.
If performance were a concern (and I don't really think it is), it should be possible to reduce the impact by assuming a sufficiently large stack guard that the majority of functions with fixed size stack frames could never leap over. Then these functions wouldn't need any runtime checks. The only checking you'd have to do is on code that uses VLAs, alloca, or such, along with the few outlier functions that use ridiculously large fixed size buffers. I don't see why you should need to touch every page.
If performance were a concern (and I don't really think it is), it should be possible to reduce the impact by assuming a sufficiently large stack guard that the majority of functions with fixed size stack frames could never leap over. Then these functions wouldn't need any runtime checks. The only checking you'd have to do is on code that uses VLAs, alloca, or such, along with the few outlier functions that use ridiculously large fixed size buffers. I don't see why you should need to touch every page.