[wp-hackers] Performance improvement -- '/%postname%/%post_id%/' over '/%postname%/'?

[Aahan Krish]

I am building a WordPress Multisite network for my college. One of the
subsites works like a bookmarking service where registered students can
share useful links; each post is equivalent to a bookmark. (Custom fields &
meta boxes are used for custom UI in post editor.)

Considering that many posts are made each day (upwards 50), which of these
two permalink structures would suit us best?

/%postname%/, e.g. domain.com/sample-post/

/%postname%/%post_id%/, e.g. domain.com/sample-post/123/

Will the '/%postname%/%post_id%/' permalink structure help as the database
size grows (i.e. the no. of posts)? or can we simply stick with
'/%postname%/' no matter what?

best,
Aahan