How to host a huge website on Craft (10k pages, over a dozen languages, 2GB database)
"Digital Ocean through Forge" is a good solution. Sounds like you're on a well-powered droplet as well.

I'd recommend moving your assets into the cloud to speed things up a bit. Something like Amazon S3 with CloudFront.

Honestly, the biggest drag is probably the use of multiple locales. Craft is making duplicates of pretty much all of the content in your database, whether you need it or not. It's also contributing to the massive size of your database.

Anecdotally... I recently removed 11 of 12 languages in a Craft 2 site (leaving only a single locale), and it reduced the size of the database by close to 90%. It made the transition to Craft 3 much, much easier.

Lastly, I'd recommend asking this question in the #devops channel on Discord. Lots of smart folks in that channel who would be able to give you even better advice than I can.