FhirPath equivalence is very costly

[ewoutkramer]

Christiaan has determined that the equivalence operations in FhirPath are very extensive, they go way beyond Matches/IsExactly, especially because they try to cast values to each other (so an int and a decimal with the same value can be determined to be equal). This is expensive, which makes things like unions, distinct etc expensive.

Can we determine that these cost is warranted, e.g. is equality indeed defined as we have written it now? If not, can we simplify?