I think it is likely that there is a slow/high latency part of the connection. This is usually represented to the user by showing a loading spinner or somethin

I think it is likely that there is a slow/high latency part of the connection. This is usually represented to the user by showing a loading spinner or something like that. However, it is using some partial reloading in the background instead of just following a link, and as a result is not letting the browser tell me that it is loading, and it doesn't have any sign of loading presented otherwise.