Strange execution time of blueprint functions

So I’ve got one problem in my project so I recreated very similar issue in simple project. Here is what I do:
I have a function which is a little bit tough on execution. It’s okay to execute it once in a while but sometimes I need to execute it multiple times (let’s say ten). If I do it all in one frame I get very noticeable freeze (about 15 ms, and sometimes I need to execute much more). So I thought that I can simply execute it once per frame and get very good performance but… I get very unexpected results. In pic below you can see all this situations combined to one picture:

39050-bp_func_exec_time.png

I didn’t move vertically this graphs (you can see that blue one is in the same place) so everything is in correct scale)

So I don’t actually see a difference between calling function ten times but in one frame and executing it each frame but only once. So why? Is this some kind of blueprint “feature” and can be avoided only with c++? How can I resolve such problem?

If you need, here is this test project. Just press “R”, “T” and “Y” with turn on unitgraph and you’ll get same pictures as I think.

[download project][2]