AI tng question

Hi everyone,I'm new to ttools and AI, but have manged to produce several successful files.I now have a flightplan, which has several aircraft as vfr tng's, and some as IFR tng's.All aircraft take off normally, but the vfr tng aircraft, land, slow down, and then take so long to takeoff again, that they end up skipping over the fields.Does anyone know of a way to get the vfr tng aircraft, to lift off earlier on a tng?Thanks in advance,Tomcat.