Yes, you can change the speed of the slideshow. Under the galleries/slideshow_blinds directory, open your gallery.js file and find this block of code:
delay: 6000, //ms
axis: 'vertical', //vertical,horizontal
blindSections: 28 //how many stripes
You will have to change the delay as well as the blindSections. The less delay the less blindSections you can have without the images showing up incorrectly. If you have fewer blindSections, the faster the blinds transition will be. Basically you want to give the transition enough time to go through before the next one starts or the gallery doesn't show correctly.