Performance Custom M3 API Program with REST

Hello,

I don't work with M3 but I'm doing an integration with M3 Cloud. Our REST client is going to consume data from a custom M3 API program via REST call.
This custom program would export transactional data. In the worst case, they estimate that volume of data would be 1.500.000 transactional records.

Has any one experience with this kind of calls so can add feedback about potential issues exporting that amount of data from a custom M3 API program being called remotely with REST?

And let's say we have 40 divisions running the same program (with different inputs). We would be talking about 50 millions of records in total from different calls...

Any feedback is more than welcome.

Thanks