I am not sure what we can do here as this URL is something that has to be fetched for the data saver users.

We have UMA around recording the time taken to fetch this request, and overall the latency is going down with time(http://shortn/_HRWlhLJ5Hq and http://shortn/_8bmmyePAFp). It is possible that in this case, there was some packet loss, and that increased the latency to > 5 seconds. 

If there is nothing actionable, I would prefer to close this bug as WAI.

Thanks for the investigation! This doesn't seem to cause any visible issues (like slowing startup down), so closing as WAI.