Is there a faster way to encode JPG than EncodeToJPG?

The platform can be WIndows or Linux, it's a server app. The users connect to my app through HTTP. My app need to render things and send it back to users as jpg as quick as possible. For now, I am using just Unity's EncodeToJPG and send it through System.IO.Stream. But i feel there should be some way faster. Also, EncodeToJPG can only run in main thread.

Do you have any suggestion?

Edit: Also i am using ReadPixels after WaitForEndOfFrame. but it can be faster also