This feels like a really dumb question, but I couldn't easily find an answer for it. Is there a way to set values for list/records or just load a record using the External ID as opposed to the Internal ID? Feels really silly to have to do a search for every record if I already have a unique key.

You can only load a record by internal id. Are you asking about setting a list/record field by id?

Create a complex filter using

'OR'

.

Yes, setting a list/record field by ID. Sound like I have to use internal ID. Just was wondering if I could use external ID since I have that in my other system and have to pass like 40,000 records (with a bunch of line items each), so really looking to shave any performance I can.