@oldwrinkly: Just tested the latest cwsoft-foldergallery module (master branch) on a clean SS 3.1.0, SS 3.1.1 and SS 3.1.2 installation using each time the standard theme simple on Windows 7 with PHP 5.4.7. The gallery and the implemented features work as expected.
Please bear in mind to synchronize the files in the SilverStripe backend in case you uploaded the images via FTP, otherwise the dropdown box doesn't work. If no images appear in the Frontend, remember to flush the cache, as most likely the thumbnail images needs to be recreated.
@AndiC: Did some tests with multiple albs and more than 300 pictures on my local Windows test environment with PHP 5.4.7 but couldn't reproduce the slow response or progress times.
Maybe you can provide me access to your site so I can check whats going on there. My Email is listed at my GitHub repository. Guess it has to do with thumbnail creation or so during first rendering or page saving.
@AndiC: Thanks for your login details. Pushed an update to my GitHub account, which should fix the slow response times unless you have set the image sort option to 4:ExifDate. Need to implement a more stable solution for the ExifDate sort option in one of the next releases.