lag horrible lag spikes

[dkees]

ya i dont know what to do i have tried everthing from making view distance to 6 instead of 10 putting more ram right now it is getting 6 gigs and when people on my server go out and explore its not moving lag its breaking blocks type of lag 
my computer is not bad 
 
nividea geforce gt 640
8 gigs of ram 
quad core amd a10-7700k apu with radeon r7 graphics 3.0