OK, SQL Agent data, that's good, the use case fits, but you're repurposing it so how much data are we talking about? For managing SQL Agent historical data the scalar-function is fine because the volume is limited (if the instance is configured well) but if we're talking about a non-trivial amount of data you should consider switching to a home-made table-valued function instead. It will scale much better and not use anywhere near as much CPU.