An SSD drive would help, i run 2 in raid-0 configuration but i still experance delays loading other players and NPC's i know so many issues get blaimed on the server lag and a lot of it incorrectly. imo for his problem there is two possable causes if you see a drop in FPS and stuttering then this is PC related, if you jsut have terrible delay when other players pass by you but the game(fps) is still smooth then it is probably server lag.

I have the 2nd issue if i'm crafting and a player runs by it takes ages to update whats going on with my craft somtimes my player doesn't even perform the action i just see the outcome and have to guess what the orb is doing for my next action.