Manual:$wgMaxBacklinksInvalidate

Details
This was used to avoid massive HTML cache invalidation when a page is edited, and a large number of other pages depended on it, e.g. a highly used template. It was used to place a threshold value on when to skip cache invalidation if there were more than number of dependent pages, and a warning was output. If this variable was unset, (or set to the default ) then the threshold was hard-coded to a default, 200.

This variable has been removed and replaced with with.