linq2db.EntityFrameworkCore VS EFCore.BulkExtensions

https://github.com/linq2db/linq2db.EntityFrameworkCore has temp table creation & bulk data insert as well

EF Core and fast insert are two different things. Better to use appropriate extensions for that, Actually I'm the one who enabled linq2db for EF Core via linq2db.EntityFrameworkCore

Try to use linq2db.EntityFrameworkCore on top of EF Core. It has more sofisticated LINQ Provider (I'm one of the creators).

EF Core Bulk Extensions has helped me out many a day.

I have used this and found it to have everything I need. It has a dual license though but if it is for personal use you dont have to worry about that. https://github.com/borisdj/EFCore.BulkExtensions

EF Core works for me and inserting/updating several thousand records at a time. I also found this nuget that works great https://github.com/borisdj/EFCore.BulkExtensions

Using EF core with migrations. Anything that we can’t do out of the box, we can normally do with the bulk extensions (https://github.com/borisdj/EFCore.BulkExtensions). There were two specific places I had to drop back to raw SQL, one was for a specific SELECT query that needed to be optimised, the second was a stored proc doing a MERGE that we pass in a table type (upsert of 100k records)

There is however a free nuget for EF Core which supports OP's needs https://github.com/borisdj/EFCore.BulkExtensions

For EFCore v6, you're best using EFCore.BulkExtensions, to do something like this:

I've been using this library with great success: EFCore.BulkExtensions

2nd option as you're basically doing batch save changes where batch size is 100. You should put a transaction on top of all of this though and commit at the end for data integrity reasons but that's about it. Alternatively use a NuGet that can do batch save changes (Z.EntotyFramework is paid, but https://github.com/borisdj/EFCore.BulkExtensions is free).