This blog provides the detail

https://tpodolak.com/blog/2017/12/13/asp-net-core-memorycache-getorcreate-calls-factory-method-multiple-times/

We see poor performance in 1 in 10 queries due to multiple invokes when not needed even under non high load conditions and have had to resort to a similar solution to that blog post which is not great .

This was closed with no good reason aspnet/Caching#359