+NYTProf says:
+
+ # spent 279s (237+41.8) within IkiWiki::bestlink which was called 13988949 times, avg 20µs/call:
+ # 13150827 times (222s+37.2s) by IkiWiki::PageSpec::match_link at line 2692, avg 20µs/call
+ # 829606 times (14.9s+4.51s) by IkiWiki::PageSpec::match_link at line 2687, avg 23µs/call
+ ...
+ sub bestlink ($$) {
+
+which is about half the execution time (458s on my laptop).
+
+Adding code to log each call to match_backlink indicates that a large part
+of the problem is that it evaluates the pagespec
+`backlink(plugins/goodstuff)` up to a million times, with various pages and locations.
+