Problem with hardware acceleration with Nvidia driver from app store

[Acer-Notebook-Optimus]

I have installed nvidia-driver-390 from app store and checked video player and external apps (vlc and mpv) from app store and noticed a high cpu-usage during playing vidoes. If hardware acceleration runs fine the cpu usage is about 30% for video player and 12%-25% for vlc / mpv.

vdpauinfo shows hardware acceleration works correct.

Error messages in the terminal:
video player

tux@tux-Aspire-G:~/Videos$ io.elementary.videos 'Simple Minds - Glittering Prize Acoustic.mp4'

(io.elementary.videos:6956): GLib-GIO-CRITICAL **: 21:14:27.827: g_mount_get_default_location: assertion 'G_IS_MOUNT (mount)' failed

(io.elementary.videos:6956): GLib-GIO-CRITICAL **: 21:14:27.835: g_mount_get_default_location: assertion 'G_IS_MOUNT (mount)' failed

(io.elementary.videos:6956): GLib-GIO-CRITICAL **: 21:14:27.979: g_mount_get_default_location: assertion 'G_IS_MOUNT (mount)' failed

(io.elementary.videos:6956): GLib-GIO-CRITICAL **: 21:14:27.991: g_mount_get_default_location: assertion 'G_IS_MOUNT (mount)' failed
tux@tux-Aspire-G:~/Videos$

vlc
tux@tux-Aspire-G:~/Videos$ vlc 'Simple Minds - Glittering Prize Acoustic.mp4'
VLC media player 3.0.8 Vetinari (revision 3.0.8-0-gf350b6b5a7)
[0000556c2d6d1570] main libvlc: VLC wird mit dem Standard-Interface ausgeführt. Benutzen Sie 'cvlc', um VLC ohne Interface zu verwenden.
[00007f7a18002ca0] egl_x11 gl error: cannot select OpenGL API
[00007f7a34c76740] avcodec decoder: Using NVIDIA VDPAU Driver Shared Library 390.116 Sun Jan 27 06:28:58 PST 2019 for hardware decoding
QObject::QObject: Timers cannot be stopped from another thread
tux@tux-Aspire-G:/Videos$

mpv
tux@tux-Aspire-G:~/Videos$ mpv 'Simple Minds - Glittering Prize Acoustic.mp4'
Playing: Simple Minds - Glittering Prize Acoustic.mp4
(+) Video --vid=1 () (h264 1280x720 25.000fps)
(+) Audio --aid=1 --alang=und () (aac 2ch 44100Hz)
VO does not support requested hardware decoder, or loading it failed.
AO: [pulse] 44100Hz stereo 2ch float
VO: [opengl] 1280x720 yuv420p
AV: 00:00:09 / 00:04:07 (3%) A-V: 0.000

Exiting... (Quit)
tux@tux-Aspire-G:~/Videos$

With correct working hardwaer acceleration the CPU consumption is about 4% to 9% normaly for the video app (vlc / mpv).

Hope this was helpful!

[Acer-Notebook-Optimus]

A small mistake I made:
If hardware acceleration runs fine the cpu usage for vlc / mpv is normaly between 4% to 10%. But vlc and mpv uses 12% to 25% of cpu consumption in elementary OS 5.1.
As far as I read, video player of elementary OS 5.1 doesn't support hardware acceleration. So the error output from video player refers to another cause.