Note that high-quality + low-bitrate AV1 setup often requires using parameters that rise the time and processing power beyond what's typically sensible in an average setup without hw encoder. And compared with h265 this would be even higher since not only is h265 less complex and faster to begin with, but it also is often hw accelerated.

Here there's a 2020 paper comparing various encoders for high quality on fullHD: https://www.researchgate.net/publication/340351958_MSU_Video_Codec_Comparison_2019_part_IV_High-Quality_Encoding_aom_rav1e_SVT-AV1_SVT-HEVC_SVT-VP9_x264_x265_ENTERPRISE_VERSION

"First place in the quality competition goes to aom [AOMedia's AV1 encoder], second place goes to SVT-AV1, and third place to x265"

And av1 codecs are younger, so I wouldn't be surprised if they have improved over the h265 ones since the article.

Here's the settings they used in aom, for reference:

aomenc.exe --width=%WIDTH% --height=%HEIGHT% 
    --fps=%FPS_NUM%/%FPS_DENOM% --bit-depth=8 --end-usage=vbr 
    --cpu-used=0 --target-bitrate=%BITRATE_KBPS% --ivf --threads=32 
    --tune=ssim -o %TARGET_FILE% %SOURCE_FILE%