I7 CPU, Windows 10 x64 pro, 32GB, Geforce 750Ti 2GB, SSD, AD 17.1.9 - No problems, AD 18 - skid, skid, crash.
AD 17.1.9 - No problem connecting to my personal vault server.
AD 18 - Nope, need Nexus, I had issues with Nexus and local libraries, so so complicated, still have 2 tickets raised with Altium with no resolution.
Best feature about AD18 - Half the installer size, bit faster to launch, pretty much it.
AD 17 Takes around 10 seconds from icon to workspace. That RAM and SSD makes a difference.