Don't equalise the heights when only one element exists in a row.
Separated the processing of each group to be equalised.
Combined setting the vertical alignment and overriding the minimum height of elements to be equalised into one call.
Split setting the vertical alignment and overriding the minimum height of elements into a separate loop and detached the elements to reduce the number of reflows and repaints.
Split setting the height of elements into a separate loop and detached the elements to reduce the number of reflows and repaints.
Added working example for equal height plugin.
Moved declarations to appropriate scope.
Cached $( this ).
Substituted '!== -1' for '>= 0' and '-= 1' for '--' in for loops.
Merge pull request #3950 from thomasgohard/optimisation-equal-height

[Equal height] Plugin optimisation