Why does the Matlab Profiler say there is a bottleneck on the 'end' statement of a 'for' loop?

Question

So, I've recently started using Matlab's built-in profiler on a regular basis, and I've noticed that while its usually great at showing which lines are taking up the most time, sometimes it'll tell me a large chunk of time is being used on the end statement of a for loop.

Now, seeing as such a line is just used for denoting the end of the loop, I can't imagine how it could use anything other than a trivial amount of processing.

I've seen a specific version of this question asked on matlab central, but a consensus didn't seem to be reached.

EDIT: Here's a minimal example of this problem:

for i =1:1000
    x = 1;
    x = [x 1];
    % clear x;
end

Even if you uncomment the clear, the end line still takes up a lot of computation (about 20%), and the clear actually increases the absolute amount of computation performed by the end line.

Answer 1

When I've seen this in my code, it's been the deallocation of large temporaries created in the loop. Each new variable created in the loop is deallocated at the end.