Why are bytes being escaped in a binary blob? The reason to use surrogateescape is when you have data that is mostly text, should be processed as text, but can have occasional binary data.  That wouldn't seem to apply to a database binary blob.

But that aside, if you want to submit a patch to speed up surrogateescape without changing its functionality, I'm sure it would be considered.  It would certainly be useful for the email library, which currently does do the stupid thing of encoding binary message attachments using surrogateescape (and I'm guessing the reason pymysql does it is something similar to why email does it: the code would need to be significantly reorganized to do things right).