Looking      basic_terraform_links file    (D:\Program Files (x86)\Stellaris\common\terraform (perhaps on different versions of different ways).

Insert        duration = 1         in all rows between      

to = *****    and     #cost      

and between      to = *****     and      energy = ****

Example:

# Arctic to Ocean
terraform_link = {
from = "pc_arctic"
to = "pc_ocean"

duration = 1

#cost
energy = 1500
resources = {

I typed a duration of 900 and it became more interesting to play, because 3600 days of terraforming is too long.

Author: LordKINE