One of my lengthy question was marked duplicated because there were too many confusions. I believe it was clearly not a duplicate. My doubt is totally different and it is not answered there. So I'm asking it again, but only the major doubt per question.
As you know, Illustrator becomes slow when you work on large JPEG/PNG photos and typography. I need to design a 3x4 feet (36x48 inches) standee. So I currently design at actual dimensions, (3x4 feet, 300 PPI). I put 300 PPI because I need to make sure photos look good even at 1 foot distance.
But this makes it little slow and lagging.
Now, what I can do is design at 12x16 inches and later scale it up.
Here are 2 concerns related to it:
a) I design at 12x16 inches, and import a high resolution image (say greater than 12000x12000 px) photo to Illustrator, which is much larger than artboard, scale it down and fit it to artboard.
NOTE: If I import the same image to 36x48 inches (300 ppi) artboard, it does completely cover up the artboard. So you get the idea of image.
Would scaling up the whole artwork at the end pixelate the photo? (Just like it happens in Photoshop, when you've not created a smart object of it, and unlike the vector objects in Illustrator which can be scaled up at any dimensions) Or doesn't Illustrator lose the information of photo when the photo is scaled down so you can scale it up at any time (obviously not exceeding the actual dimensions of the photo)?
b) If Illustrator conserves the quality of the imported photo, the only thing that remains to do is export at actual dimensions (36x48 inches). Is there any possible option in Illustrator to save the file as PDF at scaled up dimensions?
Given that all, which is a better way to design, at small dimensions or actual dimensions?
PS: Please comment if you don't understand the photo thing in a)