Create image thumbnail later

Hello, I've a script which import images from a server and link it in InDesign also some IDMS files from text source and put it in InDesign. The problem here is this file may have up to 1500 images with very large in size that takes lots of time to generate the InDesign file, So my question from this forum is:

• Can we make image import process speedy ?
• Can we generate image thumbnail later by script so that quickly it generate InDesign file and later in background keep importing the images ?
• If yes, then can some tell the way to do that ?
• If no, is there any other way to achieve this goal?

Note: Basically this script I'm using in an InDesign flex extension.

Thanks

Mac