Request information about the patch "57d10cb"

[Sam Kappen]

Could somebody explain the below patch  which is added in openssh6.8.P1?.
During the netconf test at the end customer site it causes performance
degradation. Would this cause any other issues if we revert this patch in
openssh 6.8.P1?

commit 57d10cbe861a235dd269c74fb2fe248469ecee9d
Author: markus at openbsd.org <markus at openbsd.org>
Date:   Mon Jan 19 20:16:15 2015 +0000

    upstream commit

    adapt kex to sshbuf and struct ssh; ok djm@

Regards,
Sam