The Kernel mitigations for CPU flaws like Spectre can slow down I/O operations noticably. The mitigations are however only required on systems, where users can log on via a shell and execude code. On servers, where user shells are not possible, it would be accaptable to disable the mitigations to regain the full performance. Linux has a way to disable the mitidations via prctl(2). A smb.conf option to disable the mitigations for our procecesses would be nice. See also https://www.phoronix.com/scan.php?page=news_item&px=Linux-PR_SPEC_DISABLE_NOEXEC