[Question] How much can your server handle?

[lVlal2ll3ol2o]

Just would like to know how many slots people are running on there server without lagging? For me, I'm running 30 slots with custom contents, but it would lag when the server is nearly full. Usually happens when we're all grouped together and fighting the boss or anything, our ping would shoot up 3x the amount and start warping around a bit. Our shots would be delayed firing and most of the time it wouldn't even register when that happens. Has anyone have these kind of issues on there servers and what solution you've found to remedy this problem?