Hey! I've been struggling with this for the past few hours and it took me forever to find a solution. I'm also using a Pi 4 with a CRT TV through composite output.
I was able resolve this and get audio to play at a normal speed by setting audio_pwm_mode to 2 in my config.txt file:
Code
# uncomment to enable analog audio output
dtparam=audio=on
audio_pwm_mode=2