I am trying to download dbGAP SRA samples. I used to use fastq-dump with the following command below, but for this particular project fastq-dump is running really slow because of larger datasets. So, I wanted to use fasterq-dump tool, but couldn't figure out how I could split reads per RG tags. I tried fasterq-dump with the same command below, but it looks like fasterq-dump doesn't have defline option. Any suggestions?

This is the command I use with fastq-dump:

prefetch --ngc /dbGaP/prj_222.ngc -X 9999999999999 ${SRR}    
IFS=$'\n'
RGLINES=($(sam-dump --ngc /dbGaP/prj_222.ngc ./${SRR} | sed -n '/^[^@]/!p;//q' | grep ^@RG))
args=(tee)
for RGLINE in ${RGLINES[@]}; do
unset IFS
RG=(${RGLINE})
args+=(\>\(grep -A3 --no-group-separator \"\\.${RG[1]#ID:}/[12]$\" \| gzip \> "./${SRR}.${RG[1]#ID:}.fastq-dump.split.defline.z.tee.fq.gz"\))
done
args+=(\>/dev/null)
echo "Splitting ${SRR}.sra into ${#RGLINES[@]} ReadGroups"
fastq-dump-orig.2.10.8 --ngc /dbGaP/prj_222.ngc --split-3 --defline-seq '@$ac.$si.$sg/$ri' --defline-qual '+' -Z "./${SRR}" | eval ${args[@]}