"Server Can't keep up!"

[Voxel]

I run a server off of my computer for me and my friend. After a few hours of it running i get the "can't keep up" message about every few minutes through the console. How do I fix this?

PC Specs:

GPU: GTX 570 HD

CPU: AMD FX 8350 8-core @ 4.2 ghz

RAM: 16 gb corsair vengeance DDR3 1600 mhz

(8 gb allocated to server)

I heard this problem was cause by not having enough cpu power but my CPU is great, i should be able to play bf4 while the server runs and still be fine but i get this error message when my pc is idling at desktop.