Same issue here, I'm connecting to another PC in the same room, was getting 10 MB on 13.19, getting 200kB/s now (but the speed slowly increases until the map is downloaded).

Edit : wrong post... 0.000 2016-08-29 13:22:51; Factorio 0.14.1 (build 24302, linux64, headless) 0.024 Operating system: Linux (Debian 8.5) 0.024 Program arguments: "./bin/x64/factorio" "--start-server-load-latest" 0.024 Read data path: /home/erus/Factorio_Server/factorio_14_01/d...

I'm having the same issue here : 100% usage of 1 core with no players connected, 0,5 % with one player paused (on a save created in 14.1 with only a few hours ingame).

Same here, except on a headless server, and with only one player : a server restart is the only way to unpause.