I am not sure what is causing all the constant lag, but it defently needs to be looked into. You advertice on the forums that this is a lag-free server, yet this is the WORST lag I have ever seen on servers. I know it is in the Alpha, and SMP is not that stable, but much larger servers seem to be doing fine. I believe it is one of the mods causing the lag. I suggest that you should turn off the annoying PvP mod since it is really doing more harm then benifit: Who actually enjoys it? I have used it intentionally like twice, and the other times I used it was opening chests, etc. which ended up killing the other player.
Also, if the "every 30 min. dc" is when the server is creating a back-up, I think you should set it to every hour instead of every half-hour, and post a notice in the chat saying "Creating back-up. This may cause lag and/or disconnect you."
Just a word of advice. I know we all would appreciate a less-laggy server. <object class="emojione" data="https://resources.enjin.com/1489581540/themes/core/images/emojione/svg/1f600.svg?0" type="image/svg+xml" standby=":d">:d</object>
Also, if the "every 30 min. dc" is when the server is creating a back-up, I think you should set it to every hour instead of every half-hour, and post a notice in the chat saying "Creating back-up. This may cause lag and/or disconnect you."
Just a word of advice. I know we all would appreciate a less-laggy server. <object class="emojione" data="https://resources.enjin.com/1489581540/themes/core/images/emojione/svg/1f600.svg?0" type="image/svg+xml" standby=":d">:d</object>