UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.18 Safari/537.36

Example URL:
Any youtube video both VP9 and AVC codecs

Steps to reproduce the problem:
1. Use an old netbook/computer with Intel GMA3150 or similar graphics and atom or low end CPU (no hardware video decode support)
2. Video playback on youtube 480p is completely unusable - like one frame every 5 seconds at best. The degradation is so bad that even CPUs faster than mine (also with weak GPUs) are likely also not getting usable video.

What is the expected behavior?
the current chrome stable release (ver below) provides the usable 480p performance I've had all along (about 20% frames dropped which is OK on this old box).

I've tested this many times back and forth many times so it's not a network issue.

Flash video playback is working fine.

What went wrong?
Video playback plays one frame about every five seconds.

Did this work before? Yes 66.0.3359.13

Is it a problem with Flash or HTML5? HTML5

Does this work in other browsers? Yes

Chrome version: 67.0.3396.18  Channel: beta
OS Version: 4.15.0-20-generic
Flash Version: 29.0.0.140

Contents of chrome://gpu: 

Graphics Feature Status
Canvas: Hardware accelerated
CheckerImaging: Enabled
Flash: Hardware accelerated
Flash Stage3D: Hardware accelerated
Flash Stage3D Baseline profile: Hardware accelerated
Compositing: Hardware accelerated
Multiple Raster Threads: Disabled
Native GpuMemoryBuffers: Software only. Hardware acceleration disabled
Rasterization: Software only. Hardware acceleration disabled
Surface Synchronization: Enabled
Video Decode: Unavailable
Viz Service Display Compositor: Disabled
WebGL: Hardware accelerated
WebGL2: Hardware accelerated
Driver Bug Workarounds
adjust_src_dst_region_for_blitframebuffer
clear_uniforms_before_first_program_use
count_all_in_varyings_packing
decode_encode_srgb_for_generatemipmap
disable_framebuffer_cmaa
disable_post_sub_buffers_for_onscreen_surfaces
msaa_is_slow
scalarize_vec_and_mat_constructor_args
Problems Detected
Accelerated video decode is unavailable on Linux: 137247
Disabled Features: accelerated_video_decode
Clear uniforms before first program use on all platforms: 124764, 349137
Applied Workarounds: clear_uniforms_before_first_program_use
Mesa drivers in Linux handle varyings without static use incorrectly: 333885
Applied Workarounds: count_all_in_varyings_packing
Disable partial swaps on Mesa drivers (detected with GL_RENDERER): 339493
Applied Workarounds: disable_post_sub_buffers_for_onscreen_surfaces
Always rewrite vec/mat constructors to be consistent: 398694
Applied Workarounds: scalarize_vec_and_mat_constructor_args
On Intel GPUs MSAA performance is not acceptable for GPU rasterization: 527565
Applied Workarounds: msaa_is_slow
Timer queries crash on Intel GPUs on Linux: 540543, 576991
Applied Workarounds: disable(GL_ARB_timer_query), disable(GL_EXT_timer_query)
Use GL_INTEL_framebuffer_CMAA on ChromeOS: 535198
Applied Workarounds: disable_framebuffer_cmaa
Disable partial swaps on Mesa drivers (detected with GL_VERSION): 339493
Applied Workarounds: disable_post_sub_buffers_for_onscreen_surfaces
Decode and encode before generateMipmap for srgb format textures on os except macosx: 634519
Applied Workarounds: decode_encode_srgb_for_generatemipmap
adjust src/dst region if blitting pixels outside read framebuffer on Linux Intel: 664740
Applied Workarounds: adjust_src_dst_region_for_blitframebuffer
Disable KHR_blend_equation_advanced until cc shaders are updated: 661715
Applied Workarounds: disable(GL_KHR_blend_equation_advanced), disable(GL_KHR_blend_equation_advanced_coherent)
Don't expose disjoint_timer_query extensions to WebGL: 808744
Raster is using a single thread.
Disabled Features: multiple_raster_threads
Native GpuMemoryBuffers have been disabled, either via about:flags or command line.
Disabled Features: native_gpu_memory_buffers
Viz service display compositor is not enabled by default.
Disabled Features: viz_display_compositor
Version Information
Data exported	2018-04-28T01:26:44.164Z
Chrome version	Chrome/67.0.3396.18
Operating system	Linux 4.15.0-20-generic
Software rendering list URL	https://chromium.googlesource.com/chromium/src/+/399b73768e46f9219d4868a2ad1ccb517da5347d/gpu/config/software_rendering_list.json
Driver bug list URL	https://chromium.googlesource.com/chromium/src/+/399b73768e46f9219d4868a2ad1ccb517da5347d/gpu/config/gpu_driver_bug_list.json
ANGLE commit id	d915203fe3b6
2D graphics backend	Skia/67 ad3f3c7162bc5f96fcd2203b1ea6273432ff46ef-
Command Line	/usr/bin/google-chrome-beta --flag-switches-begin --enable-tcp-fastopen --enable-zero-copy --disable-site-isolation-trials --flag-switches-end
Driver Information
Initialization time	251
In-process GPU	false
Passthrough Command Decoder	false
Direct Composition	false
Supports overlays	false
Sandboxed	true
GPU0	VENDOR = 0x8086, DEVICE= 0xa011 *ACTIVE*
Optimus	false
AMD switchable	false
Driver vendor	Mesa
Driver version	18.0.0
Driver date	
Pixel shader version	1.20
Vertex shader version	1.20
Max. MSAA samples	0
Machine model name	
Machine model version	
GL_VENDOR	Intel Open Source Technology Center
GL_RENDERER	Mesa DRI Intel(R) Pineview M
GL_VERSION	1.4 Mesa 18.0.0-rc5
GL_EXTENSIONS	GL_3DFX_texture_compression_FXT1 GL_AMD_shader_trinary_minmax GL_ANGLE_texture_compression_dxt3 GL_ANGLE_texture_compression_dxt5 GL_APPLE_object_purgeable GL_APPLE_packed_pixels GL_ARB_ES2_compatibility GL_ARB_clear_buffer_object GL_ARB_compressed_texture_pixel_storage GL_ARB_copy_buffer GL_ARB_debug_output GL_ARB_depth_texture GL_ARB_draw_buffers GL_ARB_draw_elements_base_vertex GL_ARB_explicit_attrib_location GL_ARB_explicit_uniform_location GL_ARB_fragment_program GL_ARB_fragment_shader GL_ARB_framebuffer_object GL_ARB_get_program_binary GL_ARB_get_texture_sub_image GL_ARB_half_float_pixel GL_ARB_internalformat_query GL_ARB_invalidate_subdata GL_ARB_map_buffer_alignment GL_ARB_map_buffer_range GL_ARB_multi_bind GL_ARB_multisample GL_ARB_multitexture GL_ARB_pixel_buffer_object GL_ARB_point_parameters GL_ARB_point_sprite GL_ARB_program_interface_query GL_ARB_provoking_vertex GL_ARB_robustness GL_ARB_sampler_objects GL_ARB_separate_shader_objects GL_ARB_shader_objects GL_ARB_shading_language_100 GL_ARB_shadow GL_ARB_sync GL_ARB_texture_border_clamp GL_ARB_texture_compression GL_ARB_texture_cube_map GL_ARB_texture_env_add GL_ARB_texture_env_combine GL_ARB_texture_env_crossbar GL_ARB_texture_env_dot3 GL_ARB_texture_mirrored_repeat GL_ARB_texture_non_power_of_two GL_ARB_texture_rectangle GL_ARB_texture_storage GL_ARB_transpose_matrix GL_ARB_vertex_array_object GL_ARB_vertex_attrib_binding GL_ARB_vertex_buffer_object GL_ARB_vertex_program GL_ARB_vertex_shader GL_ARB_window_pos GL_ATI_blend_equation_separate GL_ATI_draw_buffers GL_ATI_separate_stencil GL_ATI_texture_env_combine3 GL_EXT_abgr GL_EXT_bgra GL_EXT_blend_color GL_EXT_blend_equation_separate GL_EXT_blend_func_separate GL_EXT_blend_minmax GL_EXT_blend_subtract GL_EXT_compiled_vertex_array GL_EXT_copy_texture GL_EXT_draw_range_elements GL_EXT_fog_coord GL_EXT_framebuffer_blit GL_EXT_framebuffer_object GL_EXT_gpu_program_parameters GL_EXT_multi_draw_arrays GL_EXT_packed_depth_stencil GL_EXT_packed_pixels GL_EXT_pixel_buffer_object GL_EXT_point_parameters GL_EXT_polygon_offset GL_EXT_provoking_vertex GL_EXT_rescale_normal GL_EXT_secondary_color GL_EXT_separate_specular_color GL_EXT_shadow_funcs GL_EXT_stencil_two_side GL_EXT_stencil_wrap GL_EXT_subtexture GL_EXT_texture GL_EXT_texture3D GL_EXT_texture_compression_dxt1 GL_EXT_texture_compression_s3tc GL_EXT_texture_cube_map GL_EXT_texture_edge_clamp GL_EXT_texture_env_add GL_EXT_texture_env_combine GL_EXT_texture_env_dot3 GL_EXT_texture_filter_anisotropic GL_EXT_texture_lod_bias GL_EXT_texture_object GL_EXT_texture_rectangle GL_EXT_texture_sRGB GL_EXT_texture_sRGB_decode GL_EXT_vertex_array GL_IBM_multimode_draw_arrays GL_IBM_rasterpos_clip GL_IBM_texture_mirrored_repeat GL_INGR_blend_func_separate GL_KHR_context_flush_control GL_KHR_debug GL_KHR_no_error GL_MESA_pack_invert GL_MESA_window_pos GL_MESA_ycbcr_texture GL_NV_blend_square GL_NV_light_max_exponent GL_NV_packed_depth_stencil GL_NV_texgen_reflection GL_NV_texture_env_combine4 GL_NV_texture_rectangle GL_OES_EGL_image GL_OES_read_format GL_S3_s3tc GL_SGIS_generate_mipmap GL_SGIS_texture_border_clamp GL_SGIS_texture_edge_clamp GL_SGIS_texture_lod GL_SUN_multi_draw_arrays
Disabled Extensions	GL_ARB_timer_query GL_EXT_timer_query GL_KHR_blend_equation_advanced GL_KHR_blend_equation_advanced_coherent
Disabled WebGL Extensions	EXT_disjoint_timer_query EXT_disjoint_timer_query_webgl2
Window system binding vendor	SGI
Window system binding version	1.4
Window system binding extensions	GLX_ARB_create_context GLX_ARB_create_context_profile GLX_ARB_fbconfig_float GLX_ARB_framebuffer_sRGB GLX_ARB_multisample GLX_EXT_create_context_es_profile GLX_EXT_create_context_es2_profile GLX_EXT_fbconfig_packed_float GLX_EXT_framebuffer_sRGB GLX_EXT_import_context GLX_EXT_libglvnd GLX_EXT_texture_from_pixmap GLX_EXT_visual_info GLX_EXT_visual_rating GLX_MESA_copy_sub_buffer GLX_OML_swap_method GLX_SGI_make_current_read GLX_SGI_swap_control GLX_SGIS_multisample GLX_SGIX_fbconfig GLX_SGIX_pbuffer GLX_SGIX_visual_select_group GLX_INTEL_swap_event
Window manager	GNOME Shell
XDG_CURRENT_DESKTOP	GNOME
GDMSESSION	gnome
Compositing manager	Yes
Direct rendering	Yes
Reset notification strategy	0x8261
GPU process crash count	0
System visual ID	32
RGBA visual ID	155
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
R_16	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
BGRX_1010102	Software only
RGBX_1010102	Software only
BGRA_8888	Software only
RGBA_F16	Software only
YVU_420	Software only
YUV_420_BIPLANAR	Software only
UYVY_422	Software only
Display(s) Information
Info	Display[9680100370939970] bounds=[0,0 1024x600], workarea=[0,0 1024x600], scale=1, external.
Color space information	{primaries_d50_referred: [[0.5990, 0.3433], [0.3441, 0.5624], [0.1618, 0.1544]], transfer:0.0000*x + 0.0000 if x < 0.0000 else (1.0000*x + 0.0000)**2.2000 + 0.0000, matrix:RGB, range:FULL}
Bits per color component	8
Bits per pixel	24
Video Acceleration Information

I also downloaded a chromium Developer Build 68.0.3413.0 and the performance is still as bad as in the beta.

Could it possibly be related to this automated 94% performance regression report issued on Apr 19:
https://bugs.chromium.org/p/chromium/issues/detail?id=833925&q=Performance%3DMedia%20&colspec=ID%20Pri%20M%20Stars%20ReleaseBlock%20Component%20Status%20Owner%20Summary%20OS%20Modified