show - Showing of JavaFX Scene randomly delayed -

i have created javafx application (running on ubuntu, java(tm) se runtime environment (build 1.8.0_131-b11)) , have made simple test application:

  public class delayedsceneapplication extends application {     @override     public void start(stage primarystage) throws exception {         primarystage.settitle("test");         primarystage.setresizable(false);          // root.         borderpane root = new borderpane();         scene scene = new scene(root);         primarystage.setscene(scene);          // buttons box.         hbox buttonbox = new hbox();         buttonbox.setpadding(new insets(10));         buttonbox.getchildren().addall(new button("test"));          root.setbottom(buttonbox);         primarystage.show();     }   } 

the problem sometimes, after stage has been shown, scene not loaded. takes 1 second show button, more 20 seconds. when scene has not been shown yet , clicking on scene, button shows immediately. again, button shows correctly @ start up. happens, mentioned randomly. reproduce behavior 1 has restart application multiple times. did make mistake? bug? maybe not reproducible in other environment (windows, other java version, ...)?

thank much!

update: output -dprism.verbose=true option:

prism pipeline init order: es2 sw  using java-based pisces rasterizer using dirty region optimizations not using texture mask primitives not forcing power of 2 sizes textures using hardware clamp_to_zero mode opting in hidpi pixel scaling prism pipeline name = com.sun.prism.es2.es2pipeline loading es2 native library ... prism_es2     succeeded. glfactory using com.sun.prism.es2.x11glfactory (x) got class = class com.sun.prism.es2.es2pipeline initialized prism pipeline: com.sun.prism.es2.es2pipeline maximum supported texture size: 16384 maximum texture size clamped 4096 non power of 2 texture support = true maximum number of vertex attributes = 16 maximum number of uniform vertex components = 16384 maximum number of uniform fragment components = 16384 maximum number of varying components = 128 maximum number of texture units usable in vertex shader = 32 maximum number of texture units usable in fragment shader = 32 graphics vendor: intel open source technology center        renderer: mesa dri intel(r) kabylake gt2          version: 3.0 mesa 17.0.3  vsync: true vpipe: true es2resourcefactory: prism - createstockshader: fillpgram_color.frag new alphas es2resourcefactory: prism - createstockshader: texture_color.frag es2resourcefactory: prism - createstockshader: texture_lineargradient_pad.frag es2resourcefactory: prism - createstockshader: solid_texturergb.frag es2resourcefactory: prism - createstockshader: solid_texturefirstpasslcd.frag es2resourcefactory: prism - createstockshader: solid_texturesecondpasslcd.frag