It looks like MSSQL also supports base64 encoding, so sending over a file should be possible 
While this is focused on postgres, @MutedJam has made a quick overview here:
That being said, it sounds like you’d likely prefer the option of directly inserting the data in rows, instead of uploading a file? If so, you may need to either create smaller batches, or consider creating a sub-workflow that handles processing the data in smaller chunks. If your sub-workflow does all the heavy lifting of processing the data and then only returns a small amount of data back to the main workflow, you should see this speed up 
You can see more about this here.