First step to fixing lag is finding out what is causing the lag. On the Valatic Minecraft server, hit F3 and you should be able to view your FPS. Depending on your PC's hardware, your FPS and performance will vary. 60 FPS and above is a great lag-free amount of FPS. While, 30 or under can be considered laggy and under 20-10 FPS is considered basically unplayable.