CatalogFeed slow due to GetDiscountPrices

Description

In our performance test for CatalogFeed, profiling shows that GetDiscountPrices alone accounts for 50% of the time spent. It can be worse if a customer has many more promotions, even though that might not be something they want or need.

If discount prices are not necessary, you can add a setting named episerver:personalization.CalculateDiscountPrices with a value = false (it is true by default) to use the normal prices.