Oh my. No, that is on me, sorry. Take out the option.
The initial discussion of the polorts and running time threw me off. I then pictured that it was the regression that was taking a long time, but that should not be the issue here, as projection is done with 3dTproject.
Getting back to the time it takes then, your command includes a non-linear warp of the time series (even just to apply the existing warp computed in @SSwarper previously). That it takes more than 2 hours is expected. Warping the time series might take that long on its own, depending on the computer resources.
- rick