Can be to someone will the useful.
(I don’t know when there was this restriction, we found it on CCR1036 in the version 6,22)
The size of the ARP table is limited to 8192 by default.
(When exceeding this restriction process “networking” loads 100% CPU)
The limit can be set up by a command (CLI only):
/ip settings set max-arp-entries=XXXXX
PS: Thanks to support )