Did a test on my RB750Gv3 with an access liste with 8400 ip address, it did take just 5-6 seconds.
Test was to fast done so I did not get any CPU load
So I think that is is not a problem with newer routers.
/ip firewall address-list remove [/ip firewall address-list find list="FW_Block_unkown_port"]
You are going in to this access list if you try to access any port on my router that is not open. You will then be blocked to any port (also open) for 24 hours.
Here is my Splunk app showing number of IP address in the access list going down when I deleted the list. It will quickly grow up again :)
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