I'm currently writing a few performance related articles for SQL Clarity using one of my SQL Server 2014 test instances. For testing purposes I use the AdventureWorks sample database provided by Microsoft, this used to be included in the install process as an option but now you have to head over to CodePlex to download the databases. This link also includes the WorldWideImporters database for SQL Server 2016.
It's a great sample database that's freely available but the problem with AdventureWorks, particularly when resource testing, is that it isn't really that big! Thankfully Adam Machanic provides us with a script that we can run on the sample database to create some additional tables that allow us to test performance more suitably: