Two simple suggestions: The author mentioned reading in files with x "number of lines". If they are then parsing the lines into some structured format, there

Two simple suggestions: The author mentioned reading in files with x "number of lines". If they are then parsing the lines into some structured format, there are likely many opportunities to look for low cardinality aspects and to reduce object tenuring by pooling strings using either String.intern or a hashset. They should also consider increasing the eden size.