samba - Feb 2018 - Samba 4.5.15 always re-reads its configs on by each new client's connection

Hi,

After I switched to using Samba 4.5 I noticed some delays when clients
connect to the Samba server. Before I had used Samba 3.6 and there
weren't any issues with delays there.
I started samba like this:
smbd -S -F -i -d 9 -s /etc/samba/smb.conf
and saw that Samba read the configuration files every time when a client
connected to it. My share definitions are very large and reading them
can take a lot of time.

Perhaps there are any options making behavior of Samba 4 like old Samba
3? Namely that Samba will read configs only one time by starting.

Samba 4 debug log:
...
Registering messaging pointer for type 16 - private_data=(nil)
Registering messaging pointer for type 799 - private_data=(nil)
waiting for connections
[new connection here]
...
Processing section "[global]"
doing parameter workgroup = XXX
doing parameter server string = xxx
doing parameter load printers = no
doing parameter printing = bs