How do I change the slideshow speed on Windows Live Photo Gallery?

The easiest way is to use windows media center instead sadly,

Open wmc, click on Settings, pictures then slide show, and make your choices and save.

wlpg has preset slide show selections only,

The only way to adjust a slide show is to make a video file out of the files or wmv.

Then open the wmv in windows live movie maker where you can adjust it, then save the project file again as another wmv file :)

Then you can play around with the duration of the slide show, it's a bit of a pain to do this with every folder/ album you might have so i find it easier to use wmc for this.

Here's a pretty good video of doing this,

http://www.youtube.com/watch?v=eeAXLmAmhpg

Start your slideshow in Windows Live Photo.  Right click in the center of the screen while the slideshow is in progress. There should be a window that opens with a few commands. 

Play, Pause, Shuffle, Next, Back, Loop, Slideshow Speed: Slow-Med-Fast, Exit. Click one of the speed options and it should adjust immediately.

You may have to do this every time you wish to play the slideshow, not sure if the speed defaults to Medium or not.

Hope this works for you. K