Variants: How to assign a new value without altering/losing its attributes?

Hello,

I'm working with variant data with some metadata stored as attributes. The data values change frequently, but the metadata values are fairly constant.

I'm looking for a way to update the value of a variant while preserving its attributes (or equivalently, transfer the old attributes to a new variant). I know I can read the attributes from the old variant and insert them into the new one, but I'd imagine that doing this for many variants in a tight loop is wasteful of CPU cycles -- is that a valid concern? Is there a cleaner way to do this?

Thanks!