Embedded videos not loading fast enough - Vimeo / React / Next.js

Question

I'm building a website that is set up as follows:

Tech Stack:

• React >> Next.js upgrade
• Google sheets database
• Image assets via Cloudinary url (fetched in google sheets)
• Video assets via Vimeo url (fetched in google sheets)

Design

• One page website.
• Full screen containers that feature one project (of images / videos / or both).
• The user can navigate horizontally through each project by clicking left or right through the project assets.
• The user can navigate vertically through different projects.
• Lazy loading is implemented, which I think is causing the videos to load slowly (as they are only loading on demand).
• But without lazy loading implemented, the whole site slows down.

Questions:

1. Are there ways to pre-load embedded vimeo videos or pre-load x number of projects before browser refresh?
2. Do you have any tips to improve the performance and speed - would a CMS be better then fetching data from a google sheets database?

Thanks!