When using multiple audio files to create a filmstrip, it appears that PFS chooses the speed of the first audio file as the playback speed for all audio files. This causes the remaining audio files to be rendered with poor quality. You can hear cuts, glitches, and skips in the audio of all the files played after the first one.
It does not seem to matter how many audio files are used. This also occurs if you want the video to be the entire length of the played audio, so no compression or extension of any audio should be performed.
I would attach some files here, but I believe you can reproduce this simply with even a handful of images and just two audio files, but my project had five separate files with a total runtime of 8 minutes.