[Mawr]

If I understood the problem correctly, you should try calculating each format of the data once and reusing it. Something like:

    type ID {
        AsString string
        AsInt int
        AsWhatever whatever
    }

    function new type ID:
        return new ID {
            AsString: calculateAsString()
            AsInt: calculateAsInt()
            AsWhatever: calculateAsWhatever()
        }

This does assume every representation will always be used, but if that's not the case it's a matter of using some manner of a generic only-once executor, like Go's sync.Once.

[somethingsome]

But the data changes very often in place with the functions calls on it.

I agree that would be a good solution, despite that my data is huge, but it assumes the data doesn't change, or doesn't change that much.