I don't know if sound analysis (as in no false negatives or also precise as in no false positives) is just slow or if it depends on the language constructs and

I don't know if sound analysis (as in no false negatives or also precise as in no false positives) is just slow or if it depends on the language constructs and the amount of flow sensitive mutable state that is being tracked. Do you have any references on why that would be slow? That's of interest to me :) Also, perhaps is there a distinction to be made between data flow and control flow sensitivity? Seems like these kinds of analyses are increasingly added to languages for nullability tracking so it might not necessarily be that slow. Especially if the type system is of help so that the analysis can be incremental, per compilation unit.