If I install additional aircraft....

 

On the other hand, if you want to add your purchased aircraft in to Traffic X so that you can set up flight plans for them (so you see them taking off and landing at various airports just like all the other AI planes), then you must add them in to Traffic X.  If you do want to do that, then refer to this thread here: How to add new planes to TrafficX for Flight Plans.

 

---------------------------------------------------

(Note:  AI planes are mostly very frame rate friendly because they (generally) are not much more than an external shell and paint job. However, fully functional aircraft like the FSX default planes and your purchased A340 and 747 planes, all have fully functioning cockpits and instrument panels.  If you add these planes in to Traffic X to use them in your flight plans, be aware that as they fly, FSX will still be doing all the background calculations and other computational work that it normally does for the cockpit and instruments - even though it is the computer flying it and not you.  This can mean that using the FSX default aircraft and/or purchased aircraft as AI might adversely affect your frame rates. Mileage does vary, depending on your computer specs, so experimentation is the only way to know. If you use them sparingly - a handful of flight plans, one or two planes here and there - then that usually is a good compromise and works well.)