In GrandNode to improve store performance, if you are using load balancer and shared memory, you need to configure Redis caching. You are able to do it by enabling it in appsettings.json file.
//Redis support (used by web farms, Azure, etc). Find more about it at https://azure.microsoft.com/en-us/documentation/articles/cache-dotnet-how-to-use-azure-redis-cache/
Just change the value on True and provide correct connection string.