It’s definitely enough but obviously it depends on how many instances you use, how many and what kinds of effects etc.
I’m still working on a 9 year old i7 920 (see signature), using East West stuff, Kontakt, Omnisphere and plenty of other virtual instruments. Korg Arp Odyssey emulation is where my CPU draws the line. It works but I have to freeze/render anything made with it. With Cubase itself I have no performance issues.
That said, I am building a new DAW computer in few weeks.