I've been dealing with this problem for several days. I need to import around 1,600,000 nodes (one time). Everything is set correctly, but the speed is horrible.
Both on the shared server and on the localhost (WAMP and attempts to set the optimal my.ini file). The import is simply horribly slow and after importing 400,000 nodes is even slower.
I understand that processing in Drupal 8 happens per item, but how to set up / edit the import to make it faster?
Well, in the end, I dared to get on the train and started with Migrate CSV and Migrate Tools + Drush.
It looks, it works much better.
