Civilization is just very CPU demanding, it's the way it is.
It's a game that also tends to gobble up any CPU cores you can throw at it, so more the merrier. - I wouldn't personally be playing it on anything less than a 6-core CPU with HT.
What hardware are you running?
AMD FX(tm)-8320 Eight-Core Processor
AMD Radeon HD 7700 Series
RAM 8 GB of Something or another.
A small solid state for booting windows.
A 500 GB regular HDD of some sort.
Some sort of MSI board. I forget. A friend helped me pick the board years ago.
Maybe "for a game in 2018" you shouldn't use a CPU from 2012. To add to it AMD has a notoriously low single thread performance. Civ hasn't gotten less complex over the years.