The Performance page will give you an overview of your products' sales rank and how your items are performing over time.
You can view the best and worst performant ASINs to understand what's going on with them, It also alerts you when any of your ASINs lost their rank.
You can easily view in one table which of the ASINs is performing good, bad, or no change by sorting the trend column.
Once you would like to even look into the ASIN, click on it to view the individual performance of the selected ASIN.
This shows how the ASIN performed in its category over time letting you see its past trend.