1,450,000 iterations at 29 fps
550,000 iterations at 29 fps
That's interesting, thanks for doing the measurement. Also, IIRC, Python doesn't evaluate the range(0,550000) statement every iteration in a for loop (otherwise it'd be even slower!), so a function call wouldn't even things up.
I can explain why the For condition shows up as so fast: the per-iteration overheads of the loop conditions in Construct are actually incredibly low - comparable to the overheads of a C++ loop. The real work comes in the overhead of executing actions, conditions and expressions (each of which involve a for-each and execution of function pointers which are comparatively expensive for C++), as well as the list processing of conditions which pick from a list of instances. None of that is present in the events in your test.
If it interests anybody, the For condition with no actions or subevents, in a release build, with a good branch-predicting CPU, effectively comes down to this: