Multi-Threading

I would like to send my checks to the API in threads so i can do them concurrently. I cannot find any help here on this issue. Could you please assist me on what i must do in order to send a folder that has multiple images of individual bank checks in a thread each, how many can i send at once, and how many can i send per time unit (say minute). I don’t see any of the rate limitations posted for V2.

Thanks