I don't run nearly that fast but I train more seriously than ever on top of a full-time software engineering job. So far I've learned:
If your running impacts your work negatively at all, don't mention it (like if you're going away to run at a national-level race, just say you're going on vacation and leave it at that). Honestly if you're even a bit tired or sick, and people know how hard you're training, they're going to start using that as justification for every negative thing you feel. My manager's wife blamed my getting the flu despite getting the vaccine on my training, even though I got the flu during my break. So try not to talk about it too much unless people ask.
Not sure what your hours are like, but I can fit in a run in the morning and a run after work no problem. The only issue is getting stuff like chores done, and I usually need to take at least one day a week to get as many chores done as possible.
I'm more productive when I run. I get my sh*t done efficiently and well. On my breaks I have more time, but it takes me longer to do things, so it doesn't really make a difference.