Q. Does Tarantool do better on multiple CPU cores? (2018)
A. No, a single instance uses up to three cores (two is really enough). With Vinyl, you may need 3-5 cores, but not more.
If you want to make things scalable, you need to shard your data across many instances. Currently, http://github.com/tarantool/vshard is the best way to shard your database.