I agree it’s odd, but 5 seconds seems like a life time on system working at 400hz.
Looking at the hardware report CPU load is below 25%, and generally everything looks clean. There are only two things I noticed and I don’t know if they’re related or not:
The GPS data transfer has the same 5 second pulse
The clock drift seems to be a lot (but I’ve noticed this before so I’m not so sure here)
