I'm currently creating my portfolio, in presentation slide format. Unfortunately, the presentation slides for my web UI screens are heavy, due to the size of the mocked-up screens, so when I export as a pdf, it's extremely heavy! 
I've tried converting the screens to png or images, but the visual quality is terrible. I've tried flattening all the screens, but it breaks all my designs... 
I can't find any solution to reduce the weight of my portfolio without altering the visual quality... do you have any advice?

I hope I have succeeded in being clear in my explanations…

thank you in advance for your advice!