macOS coreaudiod high CPU utilization with Firefox or Chrome

For weeks the fans in my MacbookPro 15" laptop have been running at full speed, the aluminum case is hot to the touch, and the battery hardly lasts for more then a few hours.

While searching for the culprit, I regularly notice the process coreaudiod is using between 10 and 20 percent of the cpu.

_coreaudiod      96616   17.4  0.1  6098756  30144   ??  Ss   13Jul21 1679:26.11 /usr/sbin/coreaudiod

Using lsof, we can narrow down what processes are utilizing the coreaudiod services:

jemurray@phalanges:~ $ lsof | grep -i coreaudio
corespeec   476 jemurray  txt       REG                1,4     3306960 1152921500312120220 /System/Library/Components/CoreAudio.component/Contents/MacOS/CoreAudio
com.apple   552 jemurray  txt       REG                1,4     3306960 1152921500312120220 /System/Library/Components/CoreAudio.component/Contents/MacOS/CoreAudio
PowerChim   773 jemurray  txt       REG                1,4     3306960 1152921500312120220 /System/Library/Components/CoreAudio.component/Contents/MacOS/CoreAudio
plugin-co  3637 jemurray  txt       REG                1,4     3306960 1152921500312120220 /System/Library/Components/CoreAudio.component/Contents/MacOS/CoreAudio
plugin-co  3639 jemurray  txt       REG                1,4     3306960 1152921500312120220 /System/Library/Components/CoreAudio.component/Contents/MacOS/CoreAudio
plugin-co  3716 jemurray  txt       REG                1,4     3306960 1152921500312120220 /System/Library/Components/CoreAudio.component/Contents/MacOS/CoreAudio
plugin-co  3901 jemurray  txt       REG                1,4     3306960 1152921500312120220 /System/Library/Components/CoreAudio.component/Contents/MacOS/CoreAudio
Microsoft 19221 jemurray  txt       REG                1,4     3306960 1152921500312120220 /System/Library/Components/CoreAudio.component/Contents/MacOS/CoreAudio
iTerm2    19362 jemurray  txt       REG                1,4     3306960 1152921500312120220 /System/Library/Components/CoreAudio.component/Contents/MacOS/CoreAudio
Messages  19397 jemurray  txt       REG                1,4     3306960 1152921500312120220 /System/Library/Components/CoreAudio.component/Contents/MacOS/CoreAudio
Google    22063 jemurray  txt       REG                1,4     3306960 1152921500312120220 /System/Library/Components/CoreAudio.component/Contents/MacOS/CoreAudio
Slack\x20 39234 jemurray  txt       REG                1,4     3306960 1152921500312120220 /System/Library/Components/CoreAudio.component/Contents/MacOS/CoreAudio
plugin-co 40796 jemurray  txt       REG                1,4     3306960 1152921500312120220 /System/Library/Components/CoreAudio.component/Contents/MacOS/CoreAudio
QuickLook 46894 jemurray  txt       REG                1,4     3306960 1152921500312120220 /System/Library/Components/CoreAudio.component/Contents/MacOS/CoreAudio
Microsoft 48972 jemurray  txt       REG                1,4     3306960 1152921500312120220 /System/Library/Components/CoreAudio.component/Contents/MacOS/CoreAudio
Microsoft 48975 jemurray  txt       REG                1,4     3306960 1152921500312120220 /System/Library/Components/CoreAudio.component/Contents/MacOS/CoreAudio
Microsoft 82923 jemurray  txt       REG                1,4     3306960 1152921500312120220 /System/Library/Components/CoreAudio.component/Contents/MacOS/CoreAudio
plugin-co 82995 jemurray  txt       REG                1,4     3306960 1152921500312120220 /System/Library/Components/CoreAudio.component/Contents/MacOS/CoreAudio
plugin-co 82996 jemurray  txt       REG                1,4     3306960 1152921500312120220 /System/Library/Components/CoreAudio.component/Contents/MacOS/CoreAudio
Music     92477 jemurray  txt       REG                1,4     3306960 1152921500312120220 /System/Library/Components/CoreAudio.component/Contents/MacOS/CoreAudio

In this example, the plugin-container process is the sandbox environment firefox uses to keep tabs isolated. I started the search here since there were so many containers running.

To narrow down the problem, I started by examining the individual tabs within firefox task manager and noticed that outlook email, outlook calendar, gmail, and google calendar were all using a significant amount of energy. For example:

To test my theory, I closed all four of these tabs and the coreaudiod CPU utilization went to zero:

_coreaudiod      96616   0.0  0.1  6098232  23836   ??  Ss   13Jul21 1679:26.69 /usr/sbin/coreaudiod

However, I use these applications throughout the day. They must be running. As a test, I opened all four tabs in safari to see if Apple did a better job with CPU utilization. Spoiler, it does. The coreaudiod process is still zero and the fans no longer run at full speed.

Why not switch to safari exclusively? Firefox and Chrome have better support for ad blocking and some other containerization plugins I use for privacy.