PrepareProductOverviewModels takes long time before cache

1 month ago
I just started dealing with a nopcommerce version: 4.1 finished project .
Page loadings at first time (with calculated prices) take a lot of time; more than 1 minute.

When I debug the code, I found the problem is caused by;
var tireProductOverviews = _productModelFactory.PrepareProductOverviewModels(tireProducts.Union(parentProducts)).ToList();

How can I speed up this code? Is there any trick?
Thanks alot for your help
1 month ago
that's not stock nopCommerce, but at first glance I would run that Union before passing it to the method to see how long it takes on its own.