How to reduce file size

Hello! In this example, I'm making a flyer with this coppery lettering. This is a 4 in by 8.5 in flyer and is not on a huge artboard. First I'm typing the words I want. Then I'm making outlines of the letters to make a shape, and I'm "Drawing inside the shape" to paste a high res image of a copper plate. I'm doing this for each letter shape, so I'm pasting in a large copper image 28 times. This file is almost 800MB! I feel like I'm taking a long way around doing something and causing a lot of heavy fuss. Can someone tell me what I should be doing instead to acheive this result with a more reasonable file size? Thank you!