Computer/FSX Optimization with REX etc. loading better

I know there are some tweaks out there for FSX, and most of them deal with frame rate, but I'm having trouble with everything loading...  sometimes things freeze... sometimes the VC doesn't load all the way, or the exterior of the planes just the windows load...  and then sometimes I get a black screen and have to shut down completely.  So I'm running several things at once... and maybe my computer just can't keep up.  Here's what I have going on...

FSX, REX Essential Plus Overdrive, Orbyx Socal scenery, Pilotedge ATC and then Flightsim GPS for ForeFlight on the ipad.  I'm flying Carenado/Alabeo planes, GTN 750/RXP GNS 530.  That's a lot of stuff... I guess...

My computer is Intel i7-5820K @ 3.30GHz; 32GB of RAM; NVIDIA GeForce GTX 980; Windows 7 Pro 64 bit... 

I guess I'm wondering if just playing with the sliders in FSX will make a difference, or if I need to tune my computer better or both?  Would the well known tweaks to the FSX.cfg help me out? or that FSX Boost?

I open to suggestions...