Comment 1 for bug 378193

I can confirm this. It seems to happen when notify-osd displays icons in the bubble:

I am using Banshee, which displays notifications with album art on track changes. One album cover is about 1.7 MB in size. This causes notify-osd to use about 10 MB more on _each_ track change when listening to this album. I tried reproducing this with notify-send -i /path/to/cover.jpg, but it does not work.