Nautilus slows to a crawl when opening a folder with images and zoom level is > 100%

[Øyvind Stegard]

Binary package hint: nautilus

If I open a folder in Nautilus containing, say, 60 images and the zoom level is 150% or more (icon view), it immediately becomes slow, unresponsive and consumes 100% CPU for a long time *after* all the images are displayed. It does not matter if thumbnails need to be generated or not (i.e. if they are pre-cached or not). Nautilus does not crash, scrolling is possible, but is extremely jerky and quite unusable. If I leave it for a while, or leave the folder entirely, CPU consumption goes back to normal, and everything seems fine. When the zoom-level is 100% or less, the problem does not occur.

Ubuntu Hardy 8.04 with proposed updates enabled.
nautilus 1:2.22.3-0ubuntu2

Here's the top of an oprofile system report where profiling was started right before loading an image folder in Nautilus (where all thumbnails have already been generated and cached before), and stopped when Nautilus CPU usage eventually goes down to normal. No other significant things were using much CPU during profiling.

Counted CPU_CLK_UNHALTED events (Unhalted clock cycles) with a unit mask of 0x00 (Unhalted core cycles) count 100000
samples % image name app name symbol name
261360 23.8005 libjpeg.so.62.0.0 libjpeg.so.62.0.0 ycc_rgb_convert
230100 20.9538 libjpeg.so.62.0.0 libjpeg.so.62.0.0 jpeg_idct_islow
134784 12.2740 no-vmlinux no-vmlinux (no symbols)
111984 10.1977 libc-2.7.so libc-2.7.so (no symbols)
106958 9.7400 libjpeg.so.62.0.0 libjpeg.so.62.0.0 decode_mcu
96097 8.7510 libgdk_pixbuf-2.0.so.0.1200.9 libgdk_pixbuf-2.0.so.0.1200.9 (no symbols)
32077 2.9211 libjpeg.so.62.0.0 libjpeg.so.62.0.0 h2v1_fancy_upsample
29647 2.6998 libjpeg.so.62.0.0 libjpeg.so.62.0.0 jpeg_fill_bit_buffer
15201 1.3843 libxul.so libxul.so (no symbols)
11441 1.0419 libpixman-1.so.0.10.0 libpixman-1.so.0.10.0 (no symbols)
9249 0.8423 libjpeg.so.62.0.0 libjpeg.so.62.0.0 decompress_onepass
...
...

Seems like a lot of time is spent in libjpeg, even though all images have already been loaded ! This gives a very poor user experience. Perhaps new thumbnails are being generated behind the scenes, even though it already displays the cached versions ?

Hardware:
Lenovo Thinkpad Z61m, Intel Core Duo 2GHz, 2GiB RAM, ATI graphics with fglrx driver.

[Sebastien Bacher (seb128)]

Thanks for the bug report. This particular bug has already been reported, but feel free to report any other bugs you find.