Why you want to implement something like that when on mobile devices you don't have a pointer?
Do you maybe want to achieve the same effect when the user drag his finger on the screen?
However, about performances, it depends on where you are planning to let the users "play" with you app.
On a desktop browser I don't thing you will notice any performances issues, but on mobile devices I think you will.
Sometimes graphic and "special effects" has to be left aside in favor of performances.
Sencha Inc Andrea Cammarata, Solutions Engineer
CEO at SIMACS
I'm planning to make the trail follow my touch. I would also only create the trail when the user touches the screen. On touch end, the trail array will be destroyed.
I'm making a playground panel, so there will be nothing on the view unless a background image I'll put as a css cls on my playground panel. So only this panel will implement the trail.