[arch-general] gnome-shell performance problems

[Pico Geyer]

Hi all.

I'm having a performance issue with gnome shell and I wonder if anyone
can provide me with some advice.
Gnome shell seems to be using a lot of my cpu resources.
 PID USER      PR  NI  VIRT  RES  SHR S  %CPU %MEM    TIME+  COMMAND
  949 pico      20   0 1923m 204m  21m S 203.3  5.4 136:04.53
gnome-shell

When I enable threaded mode in top (H) is see this:
  PID USER      PR  NI  VIRT  RES  SHR S  %CPU %MEM    TIME+  COMMAND
  953 pico      20   0 1923m 204m  21m R  50.1  5.4  31:22.91
gnome-shell
  955 pico      20   0 1923m 204m  21m R  48.7  5.4  31:41.81
gnome-shell
  952 pico      20   0 1923m 204m  21m R  47.1  5.4  31:03.14
gnome-shell
  954 pico      20   0 1923m 204m  21m R  45.1  5.4  31:22.46 gnome-shell

That is it's using about 50% of each of my cores on my quad core system.
This high cpu usage starts when I run a command that produces a lot of
output on the terminal.
For my own use case I was importing the boost repostory into git.
git svn clone http://svn.boost.org/svn/boost
But the problem can be reproduced using the  'yes' command as well.

Can anyone explain this high cpu usage?
It happens even if I minimize the window producing the output.
Is it worth submitting a bug report for it?

I'm on a T510 Lenovo laptop with an updated Arch and I'm using the
nouveau driver.

Thanks in advance for any suggestions.
Regards,
Pico