Performance

[Myk Melez]

When reviewing the big schema-changing patches going into Bugzilla 2.18, 
it's imperative for us to keep an eye out for performance regressions 
and flunk patches that produce significant ones.  It's easy for a patch 
to regress performance when changing the schema if the patch author 
doesn't pay careful attention to the structure and frequency of their 
SELECT statements and use of indexes.

Large installations like b.m.o are already straining under the weight of 
recent regressions, and we shouldn't let any significant ones slip 
through in the next cycle.

-myk