This was ongoing for all three of us from we logged on around 13:00 on saturday until we got off, maybe around 21:00 (CET).
It did get better after a restart of the server, but it started lagging again after an hour or two.

In T184924#2675906, @Bosmo wrote:

That icon means the server is stressed and running poorly, so your connection has nothing to do with it. All you can do is switch to a server that's performing better.

Update: There was a server restart, this seemed to remove the issue for a couple hours, 1-2 then it came back.