Photoshop is a difficult choice for editing CAD work because you're degrading vectors to raster. You may have to do this, but you need to take charge of the math, and pick suitable image size. Don't just drift along accepting defaults, take control at every step. A3 will be an enormous slow file if done right. I haven't looked at your files but it seems right: you made a file suitable for printing at 3x4 inches (75x100mm) only.