> The hot split problem is an example of a poor grow/shrink algorithm

Not really. With segmented stacks, when you hit the end of a stack, you must (1) allocate a new segment to extend the stack and (2) copy the current function frame to the new segment and resume execution. Then, when the function returns, you have to (3) deallocate the new segment and shrink the stack, and (4) resume execution of the last function frame on the previous stack segment.

Now, steps (1) and (3) are optional, but steps (2) and (4) are not, and incur a significant overhead (compared with non-segmented, contiguous stack, e.g. C stack).