here is a guess ... i have read here that ai aircraft fly at the stated speed in the aircraft file, therefore a jet listed at, say, 450kts flies at that speed even around the airport where real atc controllers would have it slowed way down, Faster means  they need longer patterns just to execute turns.
papa-metro usaf 1953-57

Part of the problem may be that some models just don't make good ai models.  Taking an aircraft like the DSB Tornado and making it into an ai model may work, but may not always work well.  Some are better than others at being converted to ai.  Most of the AI only fighter models I use do this as well so it's probably just a characteristic of the model.  I suppose you could try tweaking some things in the .cfg and .air files to see what happens but that may make the model unstable when it comes to flying between point A and point B.  Everything seems to be a tradeoff with AI models.