The libaom has enabled the speed 5 to increase the encoding speed significantly. To enable the multi-threading, your number of CPU threads must be larger or equal to the product of tile-columns and tile-rows, and the row-mt must be set to 1. The g is better to set to 5*fps.
Here is an example. This example is a modified version of the Google developer guide for VP9, and it has been modified to AV1. We assume that our target output video resolution is 1920x1080 with a 24 to 30 frames per second, and our cpu has 16 cores:
ffmpeg -i input.mp4 -c:v libaom-av1 -g 150 -crf 31 \
-b:v 1800k -minrate 900k -maxrate 2610k -cpu-used 5 -tile-columns 4 \
-tile-rows 4 -row-mt 1 -threads 16 -pass 1 -c:a libopus -b:a 500K \
output.webm && \
ffmpeg -i input.mp4 -c:v libaom-av1 -g 150 -crf 31 \
-b:v 1800k -minrate 900k -maxrate 2610k -cpu-used 5 -tile-columns 4 \
-tile-rows 4 -row-mt 1 -threads 16 -pass 2 -c:a libopus -b:a 500K -y \
output-1920x1080-24-30.webm