From this thread:
https://forums.oracle.com/forums/post!reply.jspa?messageID=10631320

In my opinion it is a bug in TabPane.

Sample Application: Add and remove tabs and watch the memory increase.



import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Side;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Tab;
import javafx.scene.control.TabPane;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;

public class TestApp4 extends Application {

    public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage stage) throws Exception {
        stage.setTitle("Tabs example");

        // create window holder
        final TabPane tabPane = new TabPane();
        tabPane.setSide(Side.BOTTOM);
        tabPane.setTabClosingPolicy(TabPane.TabClosingPolicy.SELECTED_TAB);
        tabPane.getTabs().add(new MyTab("First Tab"));

        // create buttons
        Button add = new Button("Add Tab");
        Button remove = new Button("Remove Tab");


        HBox hBox = new HBox(8);
        hBox.getChildren().add(add);
        hBox.getChildren().add(remove);

        add.setOnAction(new EventHandler<ActionEvent>() {

            @Override
            public void handle(ActionEvent t) {
                tabPane.getTabs().add(new MyTab("New Tab"));
                System.gc();
                System.out.println((Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory()) / 1024 + " KB");
            }
        });

        remove.setOnAction(new EventHandler<ActionEvent>() {

            @Override
            public void handle(ActionEvent t) {
                if (!tabPane.getSelectionModel().isEmpty()) {
                    tabPane.getTabs().remove(tabPane.getSelectionModel().getSelectedIndex());
                    System.gc();
                    System.out.println((Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory()) / 1024 + " KB");
                }
            }
        });


        BorderPane borderPane = new BorderPane();
        borderPane.setCenter(tabPane);
        borderPane.setTop(hBox);

        // add components to screen
        Group root = new Group();
        Scene scene = new Scene(root);

        borderPane.setPrefSize(500, 500);

        root.getChildren().add(borderPane);
        stage.setScene(scene);
        stage.centerOnScreen();
        stage.show();
    }

    class MyTab extends Tab {

        public MyTab(String title) {
            super(title);
        }
    }
}