[Samba] Low performance when using "server signing" = "mandatory"

[Adam Błaszczykowski]

Hello,
I'm experiencing very slow read/write performance, about 20 MB/s, on Samba
share when I configure the "server signing" option as "mandatory". Once I
set "server signing" to "default", the read/write performance returns to
average speed about 800 MB/s.
I am using Samba 4.9.4 on server with Intel Xeon CPU E5-2690 0 @ 2.90GHz
(32 threads) and 10 Gbit ethernet controller.
I need to set "mandatory" value for security reasons, but the performance
is unacceptable. How to solve this problem ?

Thank you.
Adam Blaszczykowski