HELP! (MINECRAFT LAGGING BAD D:)

Hey guys, ive been having HUGE problems with Server lag. I dont know why its happening. My servers use to work just fine! Now, when i try to connect to them i get on but then i cant open any chests! Then I time out and it says exactly this: "Timed Out". Im REALLY confused by this so if someone could PLEASE help me out that would be great! (if you need more info just ask!)