Advantage(s) of static over dynamic nftables sets?

[Frank Myhr <fmyhr@xxxxxxxxxxx>]

Hi,

As an nftables newbie I was a bit surprised to discover that defining a 
set as static prevents adding or deleting elements not only from the 
packet path but also from the nft command line:

#  nft add element ip ip_filter static_set { a.b.c.d }
Error: Could not process rule: Device or resource busy

Which is easily remedied by defining the set as dynamic instead.

So now I wonder: why not define every set as dynamic? Which would allow 
modification of any set's elements without having to reload the entire 
firewall -- thereby preserving accumulated counters and other stateful 
objects. Would performance and/or memory usage take a significant hit by 
doing this?

Thanks,
Frank