Report Server portal loading extremely slow

Not sure if it helps anyone else but my issue was caused by me not having a Domain Controller, we use AzureAD to authenticate users which isn't supported by SQL Server / SSRS. I use a Workgroup and Local Users set up on the SQL Server for users to authenticate (we store there username and password in Credential Manager so it is fairly seamless. I suspect this is a bug in SSRS where it is looking for a Domain Controller and not finding one so it times out the authentication. I proved this by adding a Domain Conotroller as a test and it fixed the speed issue. I guess I'll have to live with it until AzureAD is supported by SQL Server and SSRS.