But it raises a question for me, why is syncing so hard on the HD? Blockchain is about 250G, that's only a few minutes for a SATA6 drive
You're not transferring data, you're downloading and validating it. The later being very resource heavy.
When I look at the system performance it seems the HD is the bottleneck. CPU is only at 15%, RAM 3.9G/8G, Ethernet below 5%, but the HD is 100% flat.
You seem to have room for a large dbcache, that should help. Try setting it to 2 or 3 GB.
So maybe SDD will improve sync, I will try that.
In most cases the HDD is the most limiting factor in sync speed, yes.