If you get one that hangs up for more than about five minutes or so, kill the render and start checking for what might be hanging it up.
A lot of it depends on how complex or large the images are (as in either number of nodes in vector files, or number of pixels and area in engraves.)
Anything that you don’t know the source for (something you got off the internet) could be a problem if you try to load it without checking the lines to see that what you are loading came across as smooth curves with just a few nodes as opposed to short choppy disjointed segments with tens of thousands of nodes. The short choppy segment ones tend to originate in CAD programs when curved shapes are exported, and they can overwhelm the interface.
Simplifying the lines first, or reducing the size of raster images by removing unneeded backgrounds and cropping, or splitting the image into manageable parts, will make the files load faster and wind up saving a lot of time and frustration in the long run.