You might want try PDFLight by Dalim software. It's free.
https://www.dalim.com/en/products/pdflight/
It took my 28MB PDF loaded with vector art and squashed it to 1.8MB. Yes, that's not a typo.
I have the same problem - we send out PDFs to editors for a final review and picture heavy PDFs are impossible to send, they don't load right, etc. etc. This program has saved my bacon more than once.
(Disclaimer - I am not employed, sponsored, or otherwise attached to Dalim, I just found this program in desperation. It's free anyway. They're a big data company and they created this for their clients to save space.)