[PROBLEM] High CPU usage - from 'now playing' icon!?

[robin]

Chromium seems to cause extremely high CPU usage in a specific condition (as shown by 'top' command)

Hardware: Raspberry pi 3B or 3B+ or 4
Software: 32 bit moode 8.30 or 8.31.
Screen: local HDMI attached to Pi.

Previous questions on high CPU usage haven't noted a distinction between screens states. 

I observe:

CPU in 'album view' screen is 15% for the most greedy 'chromium-browse' when PLAYING or paused.

CPU in 'playback' screen is 15% for the most greedy 'chromium-browse' when PAUSED.


CPU in 'playback' screen is 70% for the most greedy 'chromium-browse' when PLAYING.

I figured it might relate to rendering on the playing screen, and found that turning off 'Now-Playing icon' in 'Preferences' removes the problem completely (i.e. CPU no longer shoots up to during play when on 'playback' screen.

I presume the tiny graphic beside the item Now Playing shouldn't take half the Pi's processor power to render!
Happy to send 'top' output, but the problem is consistent & repeatable with numerous SD cards across numerous PIs.

Is this a (known) bug, and if not, might it be looked into?

Thanks!