RFC6724 published a newer version of the default policy table used for source and destination address selection.

Without this updated policy table some addresses won't be labled correctly resulting in inferior or even unroutable addresses getting selected.

Added ULA and global address to interface.

Ran "traceroute" to a hostname which had also one ULA and one global address.

With the old policy table the ULA address would get picked as source address, with the new one the global one is correctly selected.
Tried to measure time difference between old and new policy table with dtrace on fbt:ip:ipif_select_source_v6.

So far there does not seem to be a real slowdown, but the test environment is a bit limited.
One production webserver has been running with the new policy table for ~2 months.