Blog: AT TIME ZONE Performance Issues - Inside the slow performance of AT TIME ZONE in SQL Server using xperf, and how to work around it for faster queries. sqlskills.com/blogs/jonathan… #SQLServer #SQLskills

@SQLPoolBoy I'm not sure what you've done is accurate as you need to get the offset based on the input datetime, its not fixed. If you want fixed then use switchoffset

@SQLPoolBoy Vanilla CLR function using the TimeZoneInfo class is approx 20x better than ATZ. Don’t know what MS have been doing in their implementation.