wget -i /Applications/MAMP/htdocs/data/urls.txt -O - >> /Applications/MAMP/htdocs/data/export.txt

Total wall clock time: 1h 49m 32s
Downloaded: 9999 files, 3.5M in 0.3s (28.5 MB/s)

cat /Applications/MAMP/htdocs/data/urls.txt | tr -d 'r' | xargs -P 10 $(which wget) -i - -O - >> /Applications/MAMP/htdocs/data/export.txt

Total wall clock time: 1h 40m 10s
Downloaded: 3943 files, 8.5M in 0.3s (28.5 MB/s)