New Mac Pro 6 core or 8 core help

I am getting a new Mac pro. I am trying to choose between 6 core and 8 core.



Here are my concerns



1. the 6 core is 3.5 ghz and the 8 core is 3.0 ghz. does the lower speed on the 8 core going to slow down the graphic redraw and lag in logic X and peaking cores when using certain VIs



2. Will having more cores help with Logic slowing down as I add more tracks



3. Does having the D300 or the D700 graphics card affect the speed of the redraw and graphics like spectrum speeding up.



My experience with the 2010 mac is when I open the mixer and scroll there is a delay and a lot of lag scrolling. If I have a spectrum analyzer open and then i open the edit page for a sample, the graphics on the spectrum slow down dramatically.



What will help with this? more cores or the speed ghz or graphics card. I am going to be using a 34" dell 4k display.



right now if I have Contact or UHE diva. the CPU peaks when I am trying record. What will help with this.



I don't understand the whole speed thing. articles say having more cores for multicore make the computer faster and others say more speed. help



I will have 32g of ram. should i have 64



I only do Virtual synths but large string libraries like spitfire and play hollywood strings and maybe 20 Kontact tracks.



I notice the more tracks I have that the computer slows down in Logic and I only have 20% of the Cpu used and still have 10g left. what gives.



sorry for the long post. this purchase is really expensive and I want to make the right decision

New Mac Pro 6 core or 8 core help