Ok now PreviewLineChartRenderer is even faster! That was a big slowdown when handling big data, we had to draw a huge amount of data on 2 charts. Now PreviewLineChartRenderer displays a bitmap of the data that is generated only when needed, scrolling is really smooth. Also TreeMap was removed and replaced with an ArrayList which is waaaay faster and write a custom subList() method that does the same thing than subMap() in TreeMap so we get fast subList() and fast iteration!

Still need to work a little more on the data grouping algorithm, data looks weird sometimes because of the grouping, maybe and at specific zoom levels only 1 or 2 points of the data is showed. Also, I should add the points drawing.