Print string is very slow. Blueprint is also slower than C#.
Rather than printing the results every loop, try to print the result of that after the loop is complete in a separate method. I assume your end product won’t need to just convert > convert > print
Right now you’re going into the VM layer 100k times for all this conversion from string to int to string again on every loop and the print string doesn’t help. Also if you know how to code this in C#, coding it in C++ is not much different, really.
for (int32 i = 0; i < ParsedString.Num(); i++)