UserAgent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36

Example URL:
https://www.youtube.com/watch?v=mkggXE5e2yk

Steps to reproduce the problem:
1. Goto https://www.youtube.com/watch?v=mkggXE5e2yk
2. Set video quality to 2160p60
3. Play in fullscreen and check GPU with process explorer and devtools rendering -> FPS Meter.

What is the expected behavior?
The playback should be smooth and snappy because of the GPU helping.

What went wrong?
Barely using the GPU, 5-20%.
The CPU used at 80%. For some reason Chrome can't use CPU at 99%. Another bottleneck due to Chrome's main process?

Did this work before? No 

Is it a problem with Flash or HTML5? HTML5

Does this work in other browsers? No
 Firefox v51.0.1 (32-bit)

Chrome version: 56.0.2924.87  Channel: stable
OS Version: 6.1 (Windows 7, Windows Server 2008 R2)
Flash Version: Shockwave Flash 24.0 r0

Contents of chrome://gpu: 
Graphics Feature Status
Canvas: Hardware accelerated
Flash: Hardware accelerated
Flash Stage3D: Hardware accelerated
Flash Stage3D Baseline profile: Hardware accelerated
Compositing: Hardware accelerated
Multiple Raster Threads: Enabled
Native GpuMemoryBuffers: Software only. Hardware acceleration disabled
Rasterization: Hardware accelerated
Video Decode: Hardware accelerated
Video Encode: Hardware accelerated
VPx Video Decode: Hardware accelerated
WebGL: Hardware accelerated
WebGL2: Hardware accelerated
Driver Bug Workarounds
clear_uniforms_before_first_program_use
disable_direct_composition
disable_discard_framebuffer
disable_dxgi_zero_copy_video
disable_framebuffer_cmaa
disable_nv12_dxgi_video
exit_on_context_lost
force_cube_complete
scalarize_vec_and_mat_constructor_args
texsubimage_faster_than_teximage
Problems Detected
Some drivers are unable to reset the D3D device in the GPU process sandbox
Applied Workarounds: exit_on_context_lost
TexSubImage is faster for full uploads on ANGLE
Applied Workarounds: texsubimage_faster_than_teximage
Clear uniforms before first program use on all platforms: 124764, 349137
Applied Workarounds: clear_uniforms_before_first_program_use
Always rewrite vec/mat constructors to be consistent: 398694
Applied Workarounds: scalarize_vec_and_mat_constructor_args
ANGLE crash on glReadPixels from incomplete cube map texture: 518889
Applied Workarounds: force_cube_complete
Framebuffer discarding can hurt performance on non-tilers: 570897
Applied Workarounds: disable_discard_framebuffer
Direct composition flashes black initially on Win <10: 588588
Applied Workarounds: disable_direct_composition
Zero copy DXGI video hangs on shutdown on Win < 8.1: 621190
Applied Workarounds: disable_dxgi_zero_copy_video
NV12 DXGI video hangs or displays incorrect colors on AMD drivers: 623029, 644293
Applied Workarounds: disable_dxgi_zero_copy_video, disable_nv12_dxgi_video
Limited enabling of Chromium GL_INTEL_framebuffer_CMAA: 535198
Applied Workarounds: disable_framebuffer_cmaa
Native GpuMemoryBuffers have been disabled, either via about:flags or command line.
Disabled Features: native_gpu_memory_buffers
Version Information
Data exported	2/10/2017, 12:53:13 PM
Chrome version	Chrome/56.0.2924.87
Operating system	Windows NT 6.1.7601 SP1
Software rendering list version	0
Driver bug list version	9.24
ANGLE commit id	a4aaa2de57dc
2D graphics backend	Skia/56 bf2d9e02d58ea01f1c239f7e2fc024cba140ccb1
Command Line Args	Files (x86)\Google\Chrome\Application\chrome.exe" --flag-switches-begin --enable-devtools-experiments --enable-gpu-rasterization --enable-zero-copy --ignore-gpu-blacklist --disable-smooth-scrolling --flag-switches-end
Driver Information
Initialization time	35
In-process GPU	false
Sandboxed	false
GPU0	VENDOR = 0x1002, DEVICE= 0x6738
Optimus	false
AMD switchable	false
Desktop compositing	none
Diagonal Monitor Size of \\.\DISPLAY2	21.9"
Diagonal Monitor Size of \\.\DISPLAY1	21.5"
Driver vendor	Advanced Micro Devices, Inc.
Driver version	15.301.1901.0
Driver date	2-26-2016
Pixel shader version	5.0
Vertex shader version	5.0
Max. MSAA samples	8
Machine model name	
Machine model version	
GL_VENDOR	Google Inc.
GL_RENDERER	ANGLE (AMD Radeon HD 6800 Series Direct3D11 vs_5_0 ps_5_0)
GL_VERSION	OpenGL ES 3.0 (ANGLE 2.1.0.a4aaa2de57dc)
GL_EXTENSIONS	GL_ANGLE_depth_texture GL_ANGLE_framebuffer_blit GL_ANGLE_framebuffer_multisample GL_ANGLE_instanced_arrays GL_ANGLE_lossy_etc_decode GL_ANGLE_pack_reverse_row_order GL_ANGLE_robust_client_memory GL_ANGLE_texture_compression_dxt3 GL_ANGLE_texture_compression_dxt5 GL_ANGLE_texture_usage GL_ANGLE_translated_shader_source GL_CHROMIUM_bind_generates_resource GL_CHROMIUM_bind_uniform_location GL_CHROMIUM_copy_compressed_texture GL_CHROMIUM_copy_texture GL_CHROMIUM_sync_query GL_EXT_blend_minmax GL_EXT_color_buffer_float GL_EXT_color_buffer_half_float GL_EXT_debug_marker GL_EXT_discard_framebuffer GL_EXT_disjoint_timer_query GL_EXT_draw_buffers GL_EXT_frag_depth GL_EXT_map_buffer_range GL_EXT_occlusion_query_boolean GL_EXT_read_format_bgra GL_EXT_robustness GL_EXT_sRGB GL_EXT_shader_texture_lod GL_EXT_texture_compression_dxt1 GL_EXT_texture_filter_anisotropic GL_EXT_texture_format_BGRA8888 GL_EXT_texture_norm16 GL_EXT_texture_rg GL_EXT_texture_storage GL_EXT_unpack_subimage GL_KHR_debug GL_NV_EGL_stream_consumer_external GL_NV_fence GL_NV_pack_subimage GL_NV_pixel_buffer_object GL_OES_EGL_image GL_OES_EGL_image_external GL_OES_EGL_image_external_essl3 GL_OES_compressed_ETC1_RGB8_texture GL_OES_depth32 GL_OES_element_index_uint GL_OES_get_program_binary GL_OES_mapbuffer GL_OES_packed_depth_stencil GL_OES_rgb8_rgba8 GL_OES_standard_derivatives GL_OES_texture_float GL_OES_texture_float_linear GL_OES_texture_half_float GL_OES_texture_half_float_linear GL_OES_texture_npot GL_OES_vertex_array_object
Disabled Extensions	
Window system binding vendor	Google Inc. (adapter LUID: 000000000000e35c)
Window system binding version	1.4 (ANGLE 2.1.0.a4aaa2de57dc)
Window system binding extensions	EGL_EXT_create_context_robustness EGL_ANGLE_d3d_share_handle_client_buffer EGL_ANGLE_d3d_texture_client_buffer EGL_ANGLE_surface_d3d_texture_2d_share_handle EGL_ANGLE_query_surface_pointer EGL_ANGLE_window_fixed_size EGL_ANGLE_keyed_mutex EGL_ANGLE_surface_orientation EGL_NV_post_sub_buffer EGL_KHR_create_context EGL_EXT_device_query EGL_KHR_image EGL_KHR_image_base EGL_KHR_gl_texture_2D_image EGL_KHR_gl_texture_cubemap_image EGL_KHR_gl_renderbuffer_image EGL_KHR_get_all_proc_addresses EGL_KHR_stream EGL_KHR_stream_consumer_gltexture EGL_NV_stream_consumer_gltexture_yuv EGL_ANGLE_flexible_surface_compatibility EGL_ANGLE_create_context_webgl_compatibility EGL_CHROMIUM_create_context_bind_generates_resource
Direct rendering	Yes
Reset notification strategy	0x8252
GPU process crash count	0
Compositor Information
Tile Update Mode	Zero-copy
Partial Raster	Enabled
GpuMemoryBuffers Status
ATC	Software only
ATCIA	Software only
DXT1	Software only
DXT5	Software only
ETC1	Software only
R_8	Software only
RG_88	Software only
BGR_565	Software only
RGBA_4444	Software only
RGBX_8888	Software only
RGBA_8888	Software only
BGRX_8888	Software only
BGRA_8888	Software only
YVU_420	Software only
YUV_420_BIPLANAR	Software only
UYVY_422	Software only
Diagnostics
0
b3DAccelerationEnabled	true
b3DAccelerationExists	true
bAGPEnabled	true
bAGPExistenceValid	true
bAGPExists	true
bCanRenderWindow	true
bDDAccelerationEnabled	true
bDriverBeta	false
bDriverDebug	false
bDriverSigned	false
bDriverSignedValid	false
bNoHardware	false
dwBpp	32
dwDDIVersion	11
dwHeight	1080
dwRefreshRate	60
dwWHQLLevel	0
dwWidth	1920
iAdapter	0
lDriverSize	1506000
lMiniVddSize	0
szAGPStatusEnglish	Enabled
szAGPStatusLocalized	Aktiverad
szChipType	AMD Radeon Graphics Processor (0x6738)
szD3DStatusEnglish	Enabled
szD3DStatusLocalized	Aktiverad
szDACType	Internal DAC(400MHz)
szDDIVersionEnglish	11
szDDIVersionLocalized	11
szDDStatusEnglish	Enabled
szDDStatusLocalized	Aktiverad
szDXVAHDEnglish	Not Supported
szDXVAModes	ModeMPEG2_A ModeMPEG2_C
szDescription	AMD Radeon HD 6800 Series
szDeviceId	0x6738
szDeviceIdentifier	{D7B71EE2-2478-11CF-2B76-DA20BEC2C535}
szDeviceName	\\.\DISPLAY1
szDisplayMemoryEnglish	4095 MB
szDisplayMemoryLocalized	4095 MB
szDisplayModeEnglish	1920 x 1080 (32 bit) (60Hz)
szDisplayModeLocalized	1920 x 1080 (32 bit) (60Hz)
szDriverAssemblyVersion	15.301.1901.0
szDriverAttributes	Final Retail
szDriverDateEnglish	8/10/2016 17:53:15
szDriverDateLocalized	2016-08-10 17:53:15
szDriverLanguageEnglish	English
szDriverLanguageLocalized	Engelska
szDriverModelEnglish	WDDM 1.1
szDriverModelLocalized	WDDM 1.1
szDriverName	aticfx64.dll,aticfx64.dll,aticfx64.dll,aticfx32,aticfx32,aticfx32,atiumd64.dll,atidxx64.dll,atidxx64.dll,atiumdag,atidxx32,atidxx32,atiumdva,atiumd6a.cap,atitmm64.dll
szDriverNodeStrongName	oem8.inf:ATI.Mfg.NTamd64.6.1:ati2mtag_NI:15.301.1901.0:pci\ven_1002&dev_6738
szDriverSignDate	
szDriverVersion	8.17.0010.1433
szKeyDeviceID	Enum\PCI\VEN_1002&DEV_6738&SUBSYS_00D01002&REV_00
szKeyDeviceKey	\Registry\Machine\System\CurrentControlSet\Control\Video\{CD0FE1C9-9ADD-4714-8A4E-58EAE5F34899}\0000
szManufacturer	Advanced Micro Devices, Inc.
szMiniVdd	Saknas
szMiniVddDateEnglish	n/a
szMiniVddDateLocalized	Saknas
szMonitorMaxRes	
szMonitorName	Allmän PnP-bildskärm
szNotesEnglish	No problems found.
szNotesLocalized	Inga problem påträffades.
szOverlayEnglish	Not Supported
szRankOfInstalledDriver	00E62001
szRegHelpText	
szRevision	
szRevisionId	0x0000
szSubSysId	0x00D01002
szTestResultD3D7English	Not run
szTestResultD3D7Localized	Har inte körts
szTestResultD3D8English	Not run
szTestResultD3D8Localized	Har inte körts
szTestResultD3D9English	Not run
szTestResultD3D9Localized	Har inte körts
szTestResultDDEnglish	Not run
szTestResultDDLocalized	Har inte körts
szVdd	Saknas
szVendorId	0x1002
1
b3DAccelerationEnabled	true
b3DAccelerationExists	true
bAGPEnabled	true
bAGPExistenceValid	true
bAGPExists	true
bCanRenderWindow	true
bDDAccelerationEnabled	true
bDriverBeta	false
bDriverDebug	false
bDriverSigned	false
bDriverSignedValid	false
bNoHardware	false
dwBpp	32
dwDDIVersion	11
dwHeight	1050
dwRefreshRate	60
dwWHQLLevel	0
dwWidth	1680
iAdapter	1
lDriverSize	1506000
lMiniVddSize	0
szAGPStatusEnglish	Enabled
szAGPStatusLocalized	Aktiverad
szChipType	AMD Radeon Graphics Processor (0x6738)
szD3DStatusEnglish	Enabled
szD3DStatusLocalized	Aktiverad
szDACType	Internal DAC(400MHz)
szDDIVersionEnglish	11
szDDIVersionLocalized	11
szDDStatusEnglish	Enabled
szDDStatusLocalized	Aktiverad
szDXVAHDEnglish	Not Supported
szDXVAModes	ModeMPEG2_A ModeMPEG2_C
szDescription	AMD Radeon HD 6800 Series
szDeviceId	0x6738
szDeviceIdentifier	{D7B71EE2-2478-11CF-2B76-DA20BEC2C535}
szDeviceName	\\.\DISPLAY2
szDisplayMemoryEnglish	4095 MB
szDisplayMemoryLocalized	4095 MB
szDisplayModeEnglish	1680 x 1050 (32 bit) (60Hz)
szDisplayModeLocalized	1680 x 1050 (32 bit) (60Hz)
szDriverAssemblyVersion	15.301.1901.0
szDriverAttributes	Final Retail
szDriverDateEnglish	8/10/2016 17:53:15
szDriverDateLocalized	2016-08-10 17:53:15
szDriverLanguageEnglish	English
szDriverLanguageLocalized	Engelska
szDriverModelEnglish	WDDM 1.1
szDriverModelLocalized	WDDM 1.1
szDriverName	aticfx64.dll,aticfx64.dll,aticfx64.dll,aticfx32,aticfx32,aticfx32,atiumd64.dll,atidxx64.dll,atidxx64.dll,atiumdag,atidxx32,atidxx32,atiumdva,atiumd6a.cap,atitmm64.dll
szDriverNodeStrongName	oem8.inf:ATI.Mfg.NTamd64.6.1:ati2mtag_NI:15.301.1901.0:pci\ven_1002&dev_6738
szDriverSignDate	
szDriverVersion	8.17.0010.1433
szKeyDeviceID	Enum\PCI\VEN_1002&DEV_6738&SUBSYS_00D01002&REV_00
szKeyDeviceKey	\Registry\Machine\System\CurrentControlSet\Control\Video\{CD0FE1C9-9ADD-4714-8A4E-58EAE5F34899}\0001
szManufacturer	Advanced Micro Devices, Inc.
szMiniVdd	Saknas
szMiniVddDateEnglish	n/a
szMiniVddDateLocalized	Saknas
szMonitorMaxRes	
szMonitorName	Allmän PnP-bildskärm
szNotesEnglish	No problems found.
szNotesLocalized	Inga problem påträffades.
szOverlayEnglish	Not Supported
szRankOfInstalledDriver	00E62001
szRegHelpText	
szRevision	
szRevisionId	0x0000
szSubSysId	0x00D01002
szTestResultD3D7English	Not run
szTestResultD3D7Localized	Har inte körts
szTestResultD3D8English	Not run
szTestResultD3D8Localized	Har inte körts
szTestResultD3D9English	Not run
szTestResultD3D9Localized	Har inte körts
szTestResultDDEnglish	Not run
szTestResultDDLocalized	Har inte körts
szVdd	Saknas
szVendorId	0x1002
Log Messages
[3908:6576:0210/124548.761:ERROR:mf_helpers.cc(12)] : Error in dxva_video_decode_accelerator_win.cc on line 1421
[3908:6576:0210/124548.761:ERROR:mf_helpers.cc(12)] : Error in dxva_video_decode_accelerator_win.cc on line 619
[3908:6576:0210/124548.761:ERROR:gpu_video_decode_accelerator.cc(373)] : HW video decode not available for profile 12
[3908:6576:0210/124645.301:ERROR:mf_helpers.cc(12)] : Error in dxva_video_decode_accelerator_win.cc on line 1421
[3908:6576:0210/124645.301:ERROR:mf_helpers.cc(12)] : Error in dxva_video_decode_accelerator_win.cc on line 619
[3908:6576:0210/124645.301:ERROR:gpu_video_decode_accelerator.cc(373)] : HW video decode not available for profile 12
[3908:6576:0210/124645.501:ERROR:mf_helpers.cc(12)] : Error in dxva_video_decode_accelerator_win.cc on line 1421
[3908:6576:0210/124645.501:ERROR:mf_helpers.cc(12)] : Error in dxva_video_decode_accelerator_win.cc on line 619
[3908:6576:0210/124645.501:ERROR:gpu_video_decode_accelerator.cc(373)] : HW video decode not available for profile 12
[3908:6576:0210/124704.407:ERROR:mf_helpers.cc(12)] : Error in dxva_video_decode_accelerator_win.cc on line 1421
[3908:6576:0210/124704.407:ERROR:mf_helpers.cc(12)] : Error in dxva_video_decode_accelerator_win.cc on line 619
[3908:6576:0210/124704.407:ERROR:gpu_video_decode_accelerator.cc(373)] : HW video decode not available for profile 12
GpuProcessHostUIShim: The GPU process exited normally. Everything is okay.