@Liz-ard

on my current notebook (Windows 10, 4GB ram, IntelCore-I5):

image size 2000x1500 = 270 seconds

same image, but size reduced to 1200x900 = 120 seconds


preview is quick
both sketches performed using defaults parms

Hello dinasset, - I didn't even think about that, obviously, the bigger the image, the longer it will take to work, right? at the time the image I was trying to transform was 2.78 mb

Liz,
it's not the MB dimension which is relevant, but the dimensions of width and height in pixels
My smallest example was 1200 (width) * 900 (height).
You may post here your picture, I (or someone else) can try the effect for you (just to verify the performances)

Liz,
using one of your photos, posted under a different topic, which is 1600x1000, it took 320" on my laptop, and I got as you "preview time-out";
hence, probably some other aspect of the photo is relevant for the performances, not only x*y;
maybe the number of details.