Is there a way to bypass the Same Origin Policy without use of a proxy?

I'm trying to develop an application which is hitting an API which unfortunately has 2 caveats - it doesn't have CORS enabled and has throttling in place (and pretty bad, I believe you cannot make a request more frequently than every 2 seconds).

I have a proxy which I can use to bypass this, but the issue is that the moment I have many concurrent requests, the wait overheads are going to add up as I manage the queue of requests. Of course one way to mitigate this is by having multiple proxies.

I have read the Stack Overflow Wiki post about this, but I would just like to confirm that my understanding of this is correct.

There is no way for me to bypass this by loading the data in a hidden iframe on my page precisely because CORS has not been enabled on the API's endpoint. Thanks for any help.