Animations in multiple quick windows causes high cpu usage with intel driver

import QtQuick 2.2
import QtQuick.Window 2.0

Window {
    title: qsTr("Two Window Testcase - Window 1")
    width: 640
    height: 480
    visible: true

    Rectangle {
	id: r1
	x: 50
	y: 50
	width: 75
	height: 75
	color: "red"
    }

    NumberAnimation {
      loops: Animation.Infinite
      from: 100
      to: 400
      running: true
      target: r1
      property: "width"
    }

    Window {
	title: qsTr("Two Window Testcase - Window 2")
	
	width: 640
	height: 480
	visible: true

	Rectangle {
	    id: r
	    x: 100
	    y: 100
	    width: 200
	    height: 200
	    color: "green"
	}
	
	NumberAnimation {
	  loops: Animation.Infinite
	  from: 100
	  to: 400
	  running: true
	  target: r
	  property: "width"
	}
    }
}

$ qmlscene main.qml 
qmlscene: ../../src/xcb_conn.c:186: write_vec: Assertion `!c->out.queue_len' failed.
Aborted

qmlscene: ../../src/xcb_conn.c:186: write_vec: Assertion `!c->out.queue_len' failed.

qmlscene main.qml 
qt.scenegraph.info: threaded render loop
qt.scenegraph.info: Using sg animation driver
qt.scenegraph.info: Animation Driver: using vsync: 16.67 ms
qt.scenegraph.info: Animation Driver: using vsync: 16.67 ms
qt.scenegraph.info: texture atlas dimensions: 1024x512
qt.scenegraph.info: R/G/B/A Buffers:    8 8 8 0
qt.scenegraph.info: Depth Buffer:       24
qt.scenegraph.info: Stencil Buffer:     8
qt.scenegraph.info: Samples:            -1
qt.scenegraph.info: GL_VENDOR:          Intel Open Source Technology Center
qt.scenegraph.info: GL_RENDERER:        Mesa DRI Intel(R) Haswell Mobile 
qt.scenegraph.info: GL_VERSION:         3.0 Mesa 11.2.0
qt.scenegraph.info: GL_EXTENSIONS:      GL_ATI_texture_env_combine3 GL_ARB_shader_storage_buffer_object GL_ARB_texture_env_dot3 GL_ARB_vertex_type_2_10_10_10_rev GL_EXT_framebuffer_object GL_ARB_debug_output GL_APPLE_packed_pixels GL_ARB_blend_func_extended GL_ARB_copy_buffer GL_EXT_separate_specular_color GL_ARB_texture_rectangle GL_EXT_draw_instanced GL_EXT_texture_shared_exponent GL_EXT_texture_rectangle GL_ARB_transform_feedback3 GL_ARB_provoking_vertex GL_ARB_draw_buffers GL_ARB_get_program_binary GL_ARB_point_sprite GL_ARB_texture_rgb10_a2ui GL_ARB_occlusion_query2 GL_EXT_vertex_array GL_EXT_texture_filter_anisotropic GL_EXT_bgra GL_ARB_vertex_program GL_SUN_multi_draw_arrays GL_EXT_texture_swizzle GL_NV_primitive_restart GL_ARB_sampler_objects GL_INGR_blend_func_separate GL_KHR_debug GL_EXT_stencil_wrap GL_ARB_clear_buffer_object GL_ARB_shader_atomic_counters GL_ARB_depth_buffer_float GL_EXT_provoking_vertex GL_APPLE_object_purgeable GL_ARB_framebuffer_no_attachments GL_ARB_shader_draw_parameters GL_ARB_shading_language_100 GL_EXT_texture_cube_map GL_ARB_texture_swizzle GL_ARB_explicit_uniform_location GL_NV_texture_barrier GL_ARB_multi_bind GL_ARB_vertex_array_object GL_ARB_texture_env_combine GL_ARB_shading_language_420pack GL_ARB_depth_clamp GL_AMD_performance_monitor GL_ARB_clip_control GL_ARB_ES3_compatibility GL_EXT_stencil_two_side GL_EXT_blend_func_separate GL_EXT_packed_float GL_ARB_separate_shader_objects GL_IBM_rasterpos_clip GL_ARB_transform_feedback_instanced GL_NV_conditional_render GL_EXT_compiled_vertex_array GL_ARB_uniform_buffer_object GL_ARB_get_texture_sub_image GL_EXT_blend_equation_separate GL_EXT_texture_snorm GL_ARB_internalformat_query GL_ARB_point_parameters GL_EXT_framebuffer_multisample GL_ARB_sample_shading GL_ARB_buffer_storage GL_ARB_fragment_program GL_ARB_shader_texture_image_samples GL_EXT_draw_range_elements GL_ARB_instanced_arrays GL_ARB_multisample GL_EXT_blend_minmax GL_EXT_point_parameters GL_ARB_seamless_cubemap_per_texture GL_ARB_texture_mirror_clamp_to_edge GL_EXT_texture_array GL_ARB_map_buffer_range GL_EXT_framebuffer_sRGB GL_S3_s3tc GL_ARB_framebuffer_sRGB GL_EXT_pixel_buffer_object GL_ARB_program_interface_query GL_EXT_transform_feedback GL_EXT_framebuffer_blit GL_NV_blend_square GL_AMD_shader_trinary_minmax GL_ARB_texture_cube_map GL_ANGLE_texture_compression_dxt3 GL_EXT_abgr GL_ARB_vertex_shader GL_EXT_rescale_normal GL_NV_texgen_reflection GL_ARB_shader_bit_encoding GL_ATI_blend_equation_separate GL_EXT_texture GL_NV_packed_depth_stencil GL_ARB_texture_barrier GL_ARB_clear_texture GL_ANGLE_texture_compression_dxt5 GL_ARB_timer_query GL_ARB_pixel_buffer_object GL_MESA_texture_signed_rgba GL_AMD_draw_buffers_blend GL_EXT_blend_subtract GL_ARB_draw_elements_base_vertex GL_AMD_conservative_depth GL_ARB_texture_storage GL_ARB_invalidate_subdata GL_EXT_texture_compression_s3tc GL_ARB_texture_non_power_of_two GL_ARB_shader_texture_lod GL_ARB_texture_query_levels GL_ARB_sync GL_ARB_vertex_type_10f_11f_11f_rev GL_ARB_half_float_vertex GL_OES_EGL_image GL_ARB_texture_mirrored_repeat GL_ARB_draw_instanced GL_NV_texture_rectangle GL_ARB_copy_image GL_ARB_map_buffer_alignment GL_ARB_texture_env_crossbar GL_EXT_draw_buffers2 GL_EXT_polygon_offset GL_EXT_texture3D GL_ARB_transform_feedback2 GL_ARB_framebuffer_object GL_EXT_vertex_array_bgra GL_EXT_blend_color GL_ARB_texture_border_clamp GL_ARB_texture_env_add GL_ARB_texture_multisample GL_ARB_seamless_cube_map GL_EXT_texture_lod_bias GL_EXT_packed_depth_stencil GL_ARB_vertex_attrib_binding GL_APPLE_vertex_array_object GL_OES_read_format GL_NV_light_max_exponent GL_ARB_multitexture GL_SGIS_generate_mipmap GL_SGIS_texture_border_clamp GL_SGIS_texture_edge_clamp GL_ARB_texture_rg GL_EXT_texture_sRGB_decode GL_EXT_timer_query GL_ARB_half_float_pixel GL_ARB_shading_language_packing GL_ARB_depth_texture GL_EXT_texture_sRGB GL_ARB_texture_cube_map_array GL_EXT_shader_samples_identical GL_EXT_texture_object GL_ARB_pipeline_statistics_query GL_ARB_texture_query_lod GL_ARB_texture_gather GL_ARB_shader_image_load_store GL_EXT_framebuffer_multisample_blit_scaled GL_EXT_subtexture GL_AMD_seamless_cubemap_per_texture GL_EXT_polygon_offset_clamp GL_SGIS_texture_lod GL_EXT_texture_env_add GL_MESA_pack_invert GL_ARB_arrays_of_arrays GL_EXT_shader_integer_mix GL_ATI_draw_buffers GL_ARB_window_pos GL_ARB_robustness GL_ARB_texture_compression_rgtc GL_KHR_context_flush_control GL_EXT_packed_pixels GL_EXT_texture_compression_dxt1 GL_ARB_shader_clock GL_3DFX_texture_compression_FXT1 GL_EXT_multi_draw_arrays GL_ARB_fragment_coord_conventions GL_ARB_shader_image_size GL_ARB_texture_float GL_EXT_texture_edge_clamp GL_INTEL_performance_query GL_ARB_fragment_shader GL_EXT_texture_env_combine GL_ARB_occlusion_query GL_ARB_compressed_texture_pixel_storage GL_ARB_shadow GL_ARB_explicit_attrib_location GL_NV_texture_env_combine4 GL_ARB_texture_compression GL_EXT_secondary_color GL_MESA_window_pos GL_EXT_texture_env_dot3 GL_ARB_ES2_compatibility GL_IBM_multimode_draw_arrays GL_ARB_shader_objects GL_ARB_color_buffer_float GL_EXT_texture_compression_rgtc GL_ARB_derivative_control GL_EXT_texture_integer GL_ARB_fragment_program_shadow GL_EXT_fog_coord GL_NV_depth_clamp GL_EXT_shadow_funcs GL_ARB_vertex_array_bgra GL_ARB_texture_storage_multisample GL_ARB_texture_view GL_ATI_separate_stencil GL_ARB_conservative_depth GL_IBM_texture_mirrored_repeat GL_ATI_texture_float GL_ARB_texture_compression_bptc GL_EXT_copy_texture GL_ARB_draw_buffers_blend GL_EXT_gpu_program_parameters GL_ARB_transpose_matrix GL_ARB_conditional_render_inverted GL_ARB_vertex_buffer_object
qt.scenegraph.info: Max Texture Size:  8192
qt.scenegraph.info: Debug context:     false
qt.scenegraph.info: Animation Driver: using vsync: 16.67 ms
qt.scenegraph.info: texture atlas dimensions: 1024x512

Xlib: sequence lost (0x14554 > 0x4556) in reply type 0x23!