30W I have not actually come across poor speed control by other operators but on my visit the atco had aircraft speed displayed to him to regulate his flow . If aircraft are not complying then it should be highlighted to them, and regular offenders should be contacted.
Sharklet equipped airbuses decellerate at a slower rate than a classic ,and their numbers are increasing rapidly.Trying to slowdown , descend and achieve a cda can be a challenge in one.