I am currently using
wget -m to mirror a remote FTP but the speed suck, what are the good alternative (command) so we can parallel to download in order to boost the speed up?
Take a look at lftp. It's quite a powerful ftp client that has an option for parallel downloads:
'mirror' can download several files in parallel (--parallel option) and a single file with 'pget' (--use-pget-n option).
It's available in standard debian's repository so you should have it as well in ubuntu without using 3rd party binaries or compiling it from source.