From what I've gathered FormList was understandably slower than Array properties, but I've never been able to find anything on Linked Ref lists. In all honesty, I'd rather do FormLists or LinkedRefs because they are by far more readable to people editing them (oh hey, click click lines connect here and what I think is a hash array from keywords!). And they stand lesser chance of getting messed up or deleted when the object containing array properties gets messed with.
Can any mad scientists out there offer enlightenment on the performance of these?