I started trying to use this plugin last night to little success. I have read through the forums and tried the different tricks, but none have really helped me.
Some images work fine with the thumbnails, mostly smaller pictures, but the bigger pictures I want actually on the gallery do not work. If I reduce their size sometimes that makes the thumbs work, but that also turns into a loss of quality that I do not want.
The files are ~667 X 425 and clock in at less than 30kb a piece which does not seem that large to me.
Here is an example of how it works on my site. I made 2 galleries on the page, one with small images from the sample food folder, and the one below with the images I want to use.
itsgeektime.com/gallery-test