xargs cat a file with aws cli (amazon s3 move)

I have a file called file.csv, which is a list of the files (or more precisely, file paths path in an S3 Bucket) that need to be moved to another folder in s3. This file lists 53,00,000 files. I have tried the following, but each move is taking a long time.

cat file.csv | xargs -I {} aws s3 mv s3://Bucket1/{} s3://Bucket2/{}

I am trying to speed up the process with the following:

cat file.csv | xargs -P50 -I {} aws s3 mv --recursive s3://Bucket1/{} s3://Bucket2/{}

...but it doesn't seem to be working. I also tried:

while read line; do
  echo ${line} | \
    xargs -n1 -P100 -I {} \
      aws s3 mv s3://Bucket1/{} s3://Bucket2/{} --recursive
done < file.csv

But that doesn't seem to work either. How can I run multiple aws cli commands with xargs by reading the input file?