Ok so I have a brohoster 1GB server. I've pretty much given up on trying to find the cause myself.
The lag seems to happen when people place an excessive amount of blocks at once (not using WE just spamming right-click). The lag also happens when a new player logs onto the server. I've also noticed that my server seems to take a long time "downloading terrain..." when logging in as opposed to other servers on the same IP address.
Worldedit can cause lag when you use it (Also it can crash the server).
As jefe said before, you don't need GroupManager and permissions at the same time ...
Also remember to check your server.log file, If the file is too heavy you need to delete it as this may be becausing the lag, if this does not solve your problem open a ticket. Remember that BroHoster yesterday had like 1 hour downtime with Softlayer issues.
I think you are misunderstanding me. I only have Essentials. I do not have Permissions installed. I am fully aware the Essentials comes with GroupManager and all of that.
Also, as for the lag problem, I fixed it. It all turned out to be the ExactSpawn plugin. That's what was causing the lag as players logged in. That's what was causing the "downloading terrain..." to take so long. All of that lag is gone now.
Brohoster is horrible. I belived their ******** like everyone else. My server lags and crashes all the time I would recommend switching hosts like Im doing right now..
Whenever I have had a problem with lag, I was quick to blame Brohoster for everything. It has never been Brohoster's fault for the lag. It has always been a faulty plugin or something that I couldn't quite catch at first. Their servers are VERY good. They can hold way more people than any other server provider that I know of for the great prices they offer.
Before switching, I would suggest extensively troubleshooting each plugin. Trust me, Brohoster is fine. It's your plugins.