Comment 26 for bug 129142

I made some tests, on my system hyperspace is worst offender.

GeForce 9800 GT and Core Duo 3.2Ghz with compiz 0.7.4, xserver 1.4.1 and mesa 7.0.3.

Default FPS 50:
jussi 18320 0.5 1.3 54224 28076 pts/0 SL 15:15 0:00 /usr/lib/xscreensaver/colorfire
jussi 18416 3.2 1.5 52152 31852 pts/0 RL 15:18 0:00 /usr/lib/xscreensaver/flux
jussi 18470 2.7 1.3 54612 28220 pts/0 SL 15:19 0:00 /usr/lib/xscreensaver/hufo_tunnel
jussi 18620 1.7 1.3 44076 27052 pts/0 SL 15:23 0:00 /usr/lib/xscreensaver/sundancer2
jussi 18666 6.2 1.5 54536 32604 pts/0 SL 15:25 0:01 /usr/lib/xscreensaver/euphoria
jussi 18378 6.3 1.5 51876 31532 pts/0 SL 15:17 0:01 /usr/lib/xscreensaver/fieldlines
jussi 18452 5.5 1.5 52036 31800 pts/0 SL 15:19 0:01 /usr/lib/xscreensaver/hufo_smoke
jussi 18506 4.0 1.6 55932 33080 pts/0 SL 15:20 0:01 /usr/lib/xscreensaver/lattice
jussi 18282 7.4 1.5 53468 31128 pts/0 SL 15:14 0:02 /usr/lib/xscreensaver/biof
jussi 18301 8.0 1.5 51884 31956 pts/0 SL 15:15 0:02 /usr/lib/xscreensaver/busyspheres
jussi 18526 8.8 1.6 91624 34808 pts/0 SL 15:21 0:02 /usr/lib/xscreensaver/matrixview
jussi 18582 7.8 1.5 52152 31920 pts/0 SL 15:22 0:02 /usr/lib/xscreensaver/solarwinds
jussi 18396 12.1 1.5 52432 32064 pts/0 SL 15:17 0:03 /usr/lib/xscreensaver/flocks
jussi 18546 12.9 1.1 56772 24512 pts/0 SL 15:21 0:03 /usr/lib/xscreensaver/plasma
jussi 18340 15.5 1.5 52152 31928 pts/0 SL 15:16 0:04 /usr/lib/xscreensaver/cyclone
jussi 18600 14.2 1.5 53276 31608 pts/0 SL 15:23 0:04 /usr/lib/xscreensaver/spirographx
jussi 18564 19.8 2.0 73772 42144 pts/0 SL 15:22 0:05 /usr/lib/xscreensaver/skyrocket
jussi 18432 21.5 1.8 59832 38276 pts/0 SL 15:18 0:06 /usr/lib/xscreensaver/helios
jussi 18490 52.3 2.8 92324 58268 pts/0 RL 15:20 0:15 /usr/lib/xscreensaver/hyperspace

Changing default FPS to 30 (ofcourse I could have used -x30 instead):
jussi 31992 0.3 1.0 54032 21744 pts/0 SL 15:31 0:00 /usr/lib/xscreensaver/colorfire
jussi 32031 2.1 1.5 54496 32732 pts/0 SL 15:32 0:00 /usr/lib/xscreensaver/euphoria
jussi 32090 2.6 1.5 52144 31924 pts/0 SL 15:34 0:00 /usr/lib/xscreensaver/flux
jussi 32144 1.5 1.5 54896 32660 pts/0 SL 15:35 0:00 /usr/lib/xscreensaver/hufo_tunnel
jussi 32182 2.9 1.6 56080 33380 pts/0 RL 15:36 0:00 /usr/lib/xscreensaver/lattice
jussi 32303 1.5 1.1 44072 22956 pts/0 RL 15:39 0:00 /usr/lib/xscreensaver/sundancer2
jussi 31974 5.0 1.5 51888 32020 pts/0 SL 15:31 0:01 /usr/lib/xscreensaver/busyspheres
jussi 32128 3.5 1.5 52040 31816 pts/0 SL 15:35 0:01 /usr/lib/xscreensaver/hufo_smoke
jussi 32202 5.8 1.6 91616 34804 pts/0 SL 15:37 0:01 /usr/lib/xscreensaver/matrixview
jussi 32256 4.9 1.5 52068 31772 pts/0 SL 15:38 0:01 /usr/lib/xscreensaver/solarwinds
jussi 31953 9.3 1.5 53140 31060 pts/0 SL 15:30 0:02 /usr/lib/xscreensaver/biof
jussi 32012 9.5 1.5 52152 31924 pts/0 SL 15:32 0:02 /usr/lib/xscreensaver/cyclone
jussi 32051 7.4 1.5 51880 31612 pts/0 SL 15:33 0:02 /usr/lib/xscreensaver/fieldlines
jussi 32070 7.6 1.5 52424 32064 pts/0 SL 15:33 0:02 /usr/lib/xscreensaver/flocks
jussi 32218 7.8 1.0 56764 22460 pts/0 SL 15:37 0:02 /usr/lib/xscreensaver/plasma
jussi 32238 13.2 2.1 75300 43668 pts/0 SL 15:38 0:03 /usr/lib/xscreensaver/skyrocket
jussi 32108 14.0 1.8 59804 38320 pts/0 SL 15:34 0:04 /usr/lib/xscreensaver/helios
jussi 32287 16.5 1.5 53276 31668 pts/0 RL 15:39 0:04 /usr/lib/xscreensaver/spirographx
jussi 32164 33.1 2.7 91372 57400 pts/0 SL 15:36 0:09 /usr/lib/xscreensaver/hyperspace

Resizing window size to full screen didn't change CPU usage so I assume that default settings for screen savers are simply too optimistic. So I tried hyperspace with less stars and resolution (fps 30):
jussi 409 11.7 2.7 90396 56356 pts/0 SL 15:53 0:03 /usr/lib/xscreensaver/hyperspace --stars=200 --resolution=4

Maybe we should take some modest system and tune each screensaver settings so that CPU usage doesn't go over 20-30%?