What are SFK files? I see these when ever I open audio.

Our software creates SFK files, or peak files, for all audio events imported into a project. These files contain data which helps draw the waveform on the screen. They allow files, especially large ones, to be opened quickly. In general, these files are created automatically by the program and are extremely small in size. After closing the project, they can be deleted, but will be generated again next time the software needs to display the audio file's waveform (like when you re-open the project).