QBW updates in the background as well (it supports relative and absolute timers). The widget text I posted, when put into a QWB widget (using the advanced button) updates the widget every hour on wifi, and every 6 on 2G/3G. It also shows a widget on the desktop, indicating the status of the last "get", and provides a way to force the update to happen right away by tapping it. Regardless, the script I provided should work with alarmd as well.

Why your hildon-home is running at 100%, I have no idea. When the script runs, either via alarmd or QBW it should be spawned off a separate shell process, which should be the thing eating CPU for a short time while it does the graphical overlay. Hildon-home eating CPU is something else unrelated going on.

As for the issue with multiple lows and highs, the only thing I can tell for sure if that you're using the old script. The two I released no longer outputs that information on the terminal anymore. Try getting the file from this post and un-taring it into the imagemagic folder. It should just overlay right on top and replace the script with the new one.

The new one is much faster, and doesn't use temporary files. All the updates happen in one hit, so there's no chance of multiple overlay happening.