Problem when adding bulk zip codes

I’ve encountered multiple issues when trying to set up my shipping zones through WooCommerce. FedEx has provided us with a list of zip codes for our shipping zones. We want to set up our shipping in 3 zones based on transit time (ie: zone 1= 1 day transit, zone 2= 2 day transit & zone 3= the rest of the US). When I try pasting my zip codes (about 10,000+ codes for each zone) and hit “save” the site just keeps loading forever and eventually times out. This morning I was able to save the zip codes for one of my zones but then I was unable to access the shipping tab at all after that so I had to restore yesterday’s backup on my site.

Is WooCommerce just unable to support that many zip codes or does the issue lie somewhere else? I’ve been in contact with my server provider (WP engine) and they looked into the issue and told me to contact WooCommerce support so here I am.

Any help would greatly be appreciated.