763 Aux hydraulic seems slow?

[MNBobcat]

I have a 763H and I've run a root grapple, auger, etc with it and it has always seemed fine. I just bought a halverson wood processor and it's rated for 15 GPM. My skid is supposed to flow 15 GPM. However, the hydraulic saw seems slow to me and won't hardly cut. Is there something that can cause the skid to not flow 15 GPM?

 

[foton]

I am not sure on this but I would think that if your system runs a max volume of 15 gpm you would want to run at around 80 or so percent below max flow for a good pressure cushion.