Performance cost of attribute splatting

[stefanloerwald]

Hi,

a question came to my mind reading webassembly-performance-best-practices:

Is the performance cost for CaptureUnmatchedValues only there if there are unmatched values, or is it there as soon as there is such a parameter?

Thanks
Stefan

[stefanloerwald]

@SteveSandersonMS maybe you could say something about this? Thanks!

[SteveSandersonMS]

The expense is mostly on the outbound side, i.e., when you write @attributes=SomeDictionary in your component output to pass through the unmatched parameters into output, because to render all subsequent attributes on the same element, it has to check whether or not it matches an existing entry in the dictionary. This is true even if SomeDictionary happens to be empty, because the code doesn't know it will always be empty.

On the inbound side, the expense is only for unmatched parameters, because those are the only ones added to the dictionary.