Transfering a 10 MB file takes 40 seconds with the following envrionment: NETWORK: 100 Mbps OS: Redhat ES 3.8 PERL: 5.8.0 If COPY_SIZE in SFTP.pm is changed from 8K to 24K, the performance improved to 28 Seconds. However, this is still slow comparing with Net::FTP (2 sec) or sftp (2 sec) from the command line. Serveral questions: 1)24K seems to be maximum size 2)The COPY_SIZE is used to read the file but the the buufer returning is still 4K 3)Is encrption has anything to do with it?