Why can IE slow down and where to look for the reason?

Question

JavaScript

For the second day I am in a state of total misunderstanding.
There is JS with simple arithmetic calculations, but the number of iterations is large.
Normal browsers execute it in 0.5-0.7 seconds, and IE11 in ~40! The difference is 2 orders of magnitude - where does it come from ?!
But the most interesting thing is different. As soon as I launch the built-in profiler in IE to see where such a cloud of resources goes, the execution time miraculously drops to 6-7 seconds (which is also a lot, but still an order of magnitude better). I turn off the profiler - 40, turn it on - 7. Schrödinger's cat is resting ...
I'm not asking for a ready-made solution, but tell me at least where to dig or what to read?

Answer 1

Why can IE slow down?

Because it's IE. Problematic code to the studio (attach to the question so that it is in a conspicuous place).