highslide-software/highcharts.com — pull request #945 by raylu (2012-05-07 23:45:57+00:00)
Title: handle setTooltipPoints case where low is negative

this was causing slowdowns for us for datetime x-axis

see: http://jsfiddle.net/raylu/AFBBg/
this takes longer to render the wider your screen is, but renders quickly with the `(low > 0)` fix