Of course compression/encryption takes CPU time. It turned out that an old Pentium-133 is able to encrypt and compress about 1GB/hour -- that's quite a lot. If you compile SSH with the option "--with-none" you can tell SSH to use no encryption. That saves a little performance. Here is a comprise between several download methods (during the test, a noncompressed 6MB-file was transfered from a 133MHz-Pentium-1 to a 233MHz Pentium2 laptop over a 10MBit ethernet without other load).
+-------------------+--------+----------+-----------+----------------------+ | | FTP |encrypted |compressed |compressed & encrypted| +-------------------+--------+----------+-----------+----------------------+ +-------------------+--------+----------+-----------+----------------------+ | Elapsed Time | |7.6s | 26s | 9s | 23s | +-------------------+--------+----------+-----------+----------------------+ | Throughput | 790K/s | 232K/s | 320K/s | 264K/s | +-------------------+--------+----------+-----------+----------------------+ |Compression Factor | 1 | 1 | 3.8 | 3.8 | +-------------------+--------+----------+-----------+----------------------+