why is system() so slow for remote commands?

[Ilya Knizhnik]

Dear All,

system() passthrough() and shell_exec() all execute the given command,
with their own slight differences in output, etc

what i want to do is essentially
shell_exec("ssh ip 'df -h -l' ");
for that and other commands

for some reason this takes exactly 20 seconds before it returns, so does
'system' and 'passthrough'

ssh works fine, if i do it from the commandline it takes less than a second

I also realize that I could just write a simple shell script and just
execute the script which does take about a second.

I was just wondering if anyone knows what could be the problem? and why
20 seconds?

Thanks

Ilya