Comment 6 for bug 1087040

I have actually reproduced this. This is an effect of tmux.

It's easy for me to reproduce like this...

 1. Perform a task that generates many lines of output. dmesg works. Or a long build process.
 2. While that output is scrolling, enter into scrollback mode (Alt-PgUp, for instance)
 3. Hang out there for a few seconds
 4. Press <enter> to escape out of scroll back mode
 5. Tmux will then scroll through each and every line you've missed in the mean time. If you're on a slow network connection, this can take a long time.

My workaround is to detach from the session (F6), and then reattach.