Not sure if this helps, but the only time I see the "busy" message in tracks is after I have recorded an audio track on my old P4 Laptop. It's specs are ages behind the times but it's all I have right now for a mobile rig and it works OK.
But that is the one thing that is a noticeable difference between it and my W7 64 bit machine.
With the 64 bit machine - 2 seconds and the busy thing is gone.
With the XP 32 bit laptop , the busy stays for more than a minute depending on track count and length of song.
If you scroll towards the end of the song you will see all the wave forms are blank and slowly being drawn while this is happening.
But it eventually is happy. I'm sure if I deleted the picture cache it would repeat this slow process again.
PS, you will see a big improvement overall if you go 64 bit. I sure did.