migration to MS SQL server 2017 and IIS10 is painful slow : We run complex ASP.NET MVC web platform online. 

Recently we are in the process of migration from MS SQL server 2014 and IIS 8.5 to MS SQL server 2017 and IIS 10 and afterward, everything working 3-5 times slower which is painfully annoying slow. Can anyone please HELP US?  

here is the new version after migration http://66.23.227.124/IdeaPhotoBrowser
Here is an old version  http://homez.design/IdeaPhotoBrowser 