Website With 30k Products that requires regular updates

We have a new eCommerce website launched.

We have wholesalers and have uploaded the products to WooCommerce using WP All Import. The import was slow, required some customizations and also us breaking down CSV files into 2-4k products. In other words... big overhead... slow uploads... server timeouts... total about 12+ hours if import...

The problem is now we need a means to update the products via the CSV on a regular basis for inventory, removing old products, adding new products, etc.

Ideally what I would like to see would be an eCommerce system that pulls directly from the CSV for products or at least can load via a CRON job or something of that nature on a regular basis. (again 30k + products). The kicker is the inventory levels have to be updated quickly and seamlessly (no server timeouts, etc, etc). 12 hours wouldn't be acceptable. We need this updated in an hour or so...

I don't mind weeding through kinks but I need the final product to be reliable.

So in the end, I am not sure WooCommerce is the right tool along with WP All Import. We use it because it's our primary weapon of choice.

As always your thoughts are greatly appreciated.