sed works quite different in two servers - bash

Question

I run below command with the same file on two servers, the test.txt size is 270m.
Server A runs only 9s, Server B runs about 1500s.
sed -i "s/aaa/bbb/g" test.txt;
I have checked the linux version and sed version by below command as well, they're almost the same except the server name. And both servers are with the same hardware set(3T mem, 64 core).
uname -a
Linux serverA 2.6.32-431.17.1.el6.x86_64 #1 SMP Fri Apr 11 17:27:00 EDT 2014 x86_64 x86_64 x86_64 GNU/Linux
uname --version
uname (GNU coreutils) 8.4
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Written by David MacKenzie.
sed --version
Copyright (C) 2009 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE,
to the extent permitted by law.
GNU sed home page: <http://www.gnu.org/software/sed/>.
General help using GNU software: <http://www.gnu.org/gethelp/>.
E-mail bug reports to: <bug-gnu-utils#gnu.org>.
Be sure to include the word ``sed'' somewhere in the ``Subject:'' field.
Any idea to check the cause? Thanks a lot.

Answer 1

Two thing could explain that behaviour. The most probable is that the file resides on filesystems with different performances on each machine. Use the df command to learn what filesystem is used:
df -kh <path to the directory where the file is>
It could very well be that for the fast machine it is a local filesystem, and for the slow machine it is a remote (network) filesystem. Or both remote filesystem but one on a fast network and the other one on a slower network.
The other possibility would be that one machine is being heavily used by other processes, eating all the RAM for instance, or all the CPUs, while the other one is not. You can check the current global load of the machine with the uptime command.
The first step to find the culprit would be to verify the behaviour is reproduced every time, and then enquiry about the actual physical location of the file from each computer's point of view.