if you are playing multiplayer:
do not use the fairmount sherpa or RPA 12 these ships appear to lag both the server and all clients connected.
this has been confirmed with more players i haven't had the chance to speak to yet here: http://80.95.161.114/shipsim/forum/index.php/topic,24053.0.html
the protector has had a couple of reports of making peoples game lag, i however have not noticed this so i can not confirm or deny.
towing: if you are going to tow or be towed in MP make sure that both ships are stationary when you try to hook the ropes and do 1 at a time. lots of experience with other players hooking ropes up to a friend across the sea and "magic" ropes spanning 50 miles appearing and connecting to a random player.
Crashes: yes they happen nothing we can do, but if you do crash and especially when spawning/changing ship. do not come back and spawn in the same place, this appears to make other players lag and will cause your ship to appear like the ones in this post here: http://80.95.161.114/shipsim/forum/index.php/topic,20882.msg319572.html#msg319572