Comment 3 for bug 991232

1. Steps I took that caused me to encounter the problem:
disconnect the A/C power cable from the laptop, laptop then runs on battery power

2. expected behavior:
same network speed as on A/C power

3. behaviour actually encoutered:
very slow network speed

network speed on A/C power:
bheinsius@bheinsius-Latitude-E6400:~$ ping 192.168.0.1
PING 192.168.0.1 (192.168.0.1) 56(84) bytes of data.
64 bytes from 192.168.0.1: icmp_req=1 ttl=64 time=1.62 ms
64 bytes from 192.168.0.1: icmp_req=2 ttl=64 time=1.29 ms
64 bytes from 192.168.0.1: icmp_req=3 ttl=64 time=1.29 ms
64 bytes from 192.168.0.1: icmp_req=4 ttl=64 time=1.42 ms

network speed on battery power:
bheinsius@bheinsius-Latitude-E6400:~$ ping 192.168.0.1
PING 192.168.0.1 (192.168.0.1) 56(84) bytes of data.
64 bytes from 192.168.0.1: icmp_req=1 ttl=64 time=43.4 ms
64 bytes from 192.168.0.1: icmp_req=2 ttl=64 time=63.9 ms
64 bytes from 192.168.0.1: icmp_req=3 ttl=64 time=85.6 ms
64 bytes from 192.168.0.1: icmp_req=4 ttl=64 time=108 ms

workaround from bug 651008:
-- begin quote
(This will not fix all problems for all: see comment 24.)
Disable the power saving measures implemented by /usr/lib/pm-utils/power.d/wireless.
To disable them do:
sudo touch /etc/pm/power.d/wireless

You now should have an empty file named wireless without the executable bit set in /etc/pm/power.d.
Check with:
ls -lh /etc/pm/power.d/
You should see a file like this:
-rw-r--r-- 1 root root 0 2010-12-31 18:53 wireless

Reference: man pm-powersave
-- end quote