Write or save username if cell has been changed

In my attachment, I wrote a couple of examples to explain my question.
From B3 to B8 there are some value's (date, string, number).

If a user makes a change, it should be filled in COL C
e.g.: If B3 is changed to "Steve", C3 should get the user name from the one that changed that value
e.g.: If B4 is DELETED, so made blank, C4 should get the user name
Same for the other values, so it should do the same with dates and numbers.

Is this possible without making my sheet working slow?
User name is, I guess, the windows user name? Or does excel have user names too?

Thanks in advance !!

Grts
Kristof