SWT GLCanvas slow compared to AWTGLCanvas for me

[wrobel]

Hi, I have question about how to properly(and efficiently) call OpenGL drwawing from outside SWT User Interface thread. I have a program, which I started to port from AWT to SWT. On AWT version I'm calling:

refresh = new Thread(){
		 public void run() {
				while(true){
					 if (isVisible()) awtglcanvas.repaint();
                                         Display.sync(fps);
				}
			}
		};
		refresh.setDaemon(true);	
		refresh.start();

And I was able to run it smoothly without any significant CPU overload for even fps>100.
In SWT I do:
(initialization)

this.datagl = new GLData ();
datagl.doubleBuffer = true;
swtglcanvas = new GLCanvas(shell, SWT.NONE, datagl);
swtglcanvas.setBounds(0,0,x,y);
swtglcanvas.setCurrent();
try {
	GLContext.useContext(swtglcanvas);
} catch(LWJGLException e) { e.printStackTrace(); }

and displaying in non User Interface Thread(similary):

Thread refresh = new Thread(){
			 public void run() {
					while(swt_display.isDisposed()==false){
						order_of_draw();
					        org.lwjgl.opengl.Display.sync(fps);
					}
				}
			};
			refresh.setDaemon(true);	
			refresh.start();

,where "order_of_draw();" call the following:

public void order_of_draw(){
		swt_display.asyncExec(new Runnable(){
			public void run() {
                                        someLWJGLheavyDrawing();
					swtglcanvas.swapBuffers();
				}
			}
		});
	}

However, this latter consume much of CPU at similar fps compared to AWT version(>80% cpu load, compared to ~1% in AWTGLCanvas at fps=60. At 10 fps it is ~20% cpu load versus ~0% cpu load). There must be something I do wrong, but what it is? LWJGL drawing code is identical on both version. Thanks in advance for any replies and sorry for my english.