I have never heard that word "lagga" before!!! But here it says that it has to do with when the computer "loads", but one can't do nothing at the same time, or when the computer "locks" itself ...no contact. I think that "devil" is wrong word here, "hell" is better.
So I guess that the translation is correct!
But the source text is misspelled, it shall be: "Det laggar som fan", I have correct it.