From Porto theme to GP

Hi All,

We want to migrate our current company website which is using the wordpress theme "Porto" to generatepress. I am working on a " dev or staging" version of our main website but i was curious on what is the best way to migrate all the homepage settings etc to the main website?

We do have a complex website because we have:
157 pages which is divided in 100 pages dutch, 25 in english, 7 in french and 25 in german.
We also have a webshop with around 550 items ( and expanding ) so i want to make the switch to a lighter and faster theme.
Because we have now have a loading speed around 3 secs where we lose alot of customers to.

thanks in advance!