When I got to the site, the first thing I noticed, beside the frigid temperature, was that there were some pretty fast people. I'm talking running up and down, doing all kinds of weird stretching/jumping exercises fast people. I knew I wouldn't win for sure. Then the announcer got on the mike to let us know that it was partially a trail run and that some obstacles (trees amongst other things) were blocking parts of the path. He gave everyone a free pass for not PB'ing under these conditions: "We are not even sure the course is exactly 5km!".
Then the start siren came out of nowhere and we all started along. It was quite a fast start with everybody angling for their respective places. The course followed the street for a while and then we headed for the trails where things got twisty and slippery.
I hadn't run a trail at all this season so this was refreshing. I was really glad to follow someone going roughly the same speed as me. It would have been hard to pass someone in the forest and he was able to scout the trail for me. My only worry was keeping up.
Once I got out of the woods, I was able to increase my pace a bit and run side by side with my friendly leader from the wood for a while. Then I saw people ahead and decided to go fishing and reel them in. I think I was able to overtake one or two runners before heading over to the finish line. With about 250m to go, I realized someone was challenging me so I turned the afterburners on and had a really strong finish (first time I get yellow in the speed heatmap afaik).
I'm really happy about my run. I had a bit of soreness in the ankle in the morning before the run but after warming up I didn't feel it anymore. It's not really a PB, although being my first chipped 5k so it may count as that. My Garmin agreed with my colleague's that the course was 5.15k. The reception under the trees in the forest may have introduced a bit of error...