softc0r3

This is my computer, I've only got myself and two friends playing. I currently have 8gb of DDR3 RAM. I'm highly doubtful that this is the problem considering there's never any lag or connection related problems in any other area. As well as this is not the first server I've had, nor the most people I've ever had on one. Another thing, if I start a new world and spawn some lava/water, they both flow fine. If I use any of the worlds I have that are more "developed" however, the liquids are glitchy. This is a very confusing problem.

Launcher/pack Version: Launcher version 1.0.1.3/ Tekkit 2.1.1 Operating System: Windows 7 Ultimate Version of Java: Latest, not sure which number but I just got it a few days ago. Description of Problem: When we place or remove lava/water blocks they don't fill in correctly. They do not run correctly, making it impossible to create things like cobblestone farms. It will usually end up flowing where it should, but it can sometimes take 15+ minutes to do so, and even then it doesn't always. Everything else on the server runs smoothly though, with no lagging behind or anything. Does anybody know what might be causing this, or what can be done?