Our application runs as a JFXPanel in a full screen JFrame with legacy Swing dialogue windows on linux.

When the application is run on high resolution screens (EG 2560x1440) the CPU load on the AWT EDT is noticeably higher. This is somewhat expected as the JFXPanel is forced to transfer more pixels at higher resolutions however it ties up the AWT EDT which can cause problems with legacy swing features.

Internally the JFXPanel uses a BufferedImage created using the BufferedImage constructor to store the pixels being transferred between JavaFX and Swing.
Changing the JFXPanel to create this BufferedImage using GraphicsConfiguration.createCompatibleImage can result in lower CPU load on the AWT EDT.

Using the example application below which updates the JavaFX scene at 10 Hz the following results were measured on linux.

 - JDK7u55 BufferedImage constructor : 45% of one CPU core consumed by EDT
 - JDK7u55 createCompatibleImage : 18.5% of one CPU core consumed by EDT
 - JDK8u5 BufferedImage constructor : 24% of one CPU core consumed by EDT
 - JDK8u5 createCompatibleImage : 10.5% of one CPU core consumed by EDT

The X11 configuration generated by xdpyinfo is as follows:
name of display: :0.0
version number: 11.0
vendor string: Red Hat, Inc.
vendor release number: 11004000
maximum request size: 16777212 bytes
motion buffer size: 256
bitmap unit, bit order, padding: 32, LSBFirst, 32
image byte order: LSBFirst
number of supported pixmap formats: 7
supported pixmap formats:
    depth 1, bits_per_pixel 1, scanline_pad 32
    depth 4, bits_per_pixel 8, scanline_pad 32
    depth 8, bits_per_pixel 8, scanline_pad 32
    depth 15, bits_per_pixel 16, scanline_pad 32
    depth 16, bits_per_pixel 16, scanline_pad 32
    depth 24, bits_per_pixel 32, scanline_pad 32
    depth 32, bits_per_pixel 32, scanline_pad 32
keycode range: minimum 8, maximum 255
focus: PointerRoot
number of extensions: 28
    BIG-REQUESTS
    Composite
    DAMAGE
    DOUBLE-BUFFER
    DPMS
    DRI2
    GLX
    Generic Event Extension
    MIT-SCREEN-SAVER
    MIT-SHM
    NV-CONTROL
    NV-GLX
    RANDR
    RECORD
    RENDER
    SHAPE
    SYNC
    X-Resource
    XC-MISC
    XFIXES
    XFree86-DGA
    XFree86-VidModeExtension
    XINERAMA
    XINERAMA
    XInputExtension
    XKEYBOARD
    XTEST
    XVideo
default screen number: 0
number of screens: 1

screen #0:
  print screen: no
  dimensions: 2560x1440 pixels (602x341 millimeters)
  resolution: 108x107 dots per inch
  depths (7): 24, 1, 4, 8, 15, 16, 32
  root window id: 0x2f2
  depth of root window: 24 planes
  number of colormaps: minimum 1, maximum 1
  default colormap: 0x20
  default number of colormap cells: 256
  preallocated pixels: black 0, white 16777215
  options: backing-store YES, save-unders NO
  largest cursor: 256x256
  current input event mask: 0x0
  number of visuals: 276
  default visual id: 0x21
  visual:
    visual id: 0x21
    class: TrueColor
    depth: 24 planes
    available colormap entries: 256 per subfield
    red, green, blue masks: 0xff0000, 0xff00, 0xff
    significant bits in color specification: 14 bits
  visual:
    visual id: 0x22
    class: DirectColor
    depth: 24 planes
    available colormap entries: 256 per subfield
    red, green, blue masks: 0xff0000, 0xff00, 0xff
    significant bits in color specification: 14 bits
.....

The following sample application updates a full screen JFXPanel at 10 Hz and was used to produce the figures above:

import java.awt.HeadlessException;
import java.text.SimpleDateFormat;
import java.util.Date;

import javafx.animation.AnimationTimer;
import javafx.application.Platform;
import javafx.embed.swing.JFXPanel;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.layout.BorderPane;

import javax.swing.JFrame;

public class JFXPanelTest extends JFrame {

    private Label timeLabel;

    public JFXPanelTest() throws HeadlessException {
        super("JFXPanel Test");
        setUndecorated(true);
        setExtendedState(JFrame.MAXIMIZED_BOTH);
        final JFXPanel fxPanel = new JFXPanel();
        add(fxPanel);
        Platform.runLater(new Runnable() {
            @Override
            public void run() {
                fxPanel.setScene(buildScene());
            }
        });
    }

    private Scene buildScene() {
        BorderPane fxContent = new BorderPane();
        timeLabel = new Label();
        fxContent.centerProperty().set(timeLabel);
        ClockTimer clockTimer = new ClockTimer();
        clockTimer.start();
        return new Scene(fxContent);
    }

    public static void main(String[] args) {
        JFXPanelTest fxPanelTest = new JFXPanelTest();
        fxPanelTest.setDefaultCloseOperation(EXIT_ON_CLOSE);
        fxPanelTest.setVisible(true);
    }

    private class ClockTimer extends AnimationTimer {

        private SimpleDateFormat dateFormat = new SimpleDateFormat("HH:mm:ss.S");
        private String previousTime;

        @Override
        public void handle(long arg0) {
            String currentTime = dateFormat.format(new Date());
            // truncate to tenths of a second
            currentTime = currentTime.substring(0, currentTime.length() - 2);
            if (!currentTime.equals(previousTime)) {
                timeLabel.setText(currentTime);
                previousTime = currentTime;
            }
        }
    }
}