Concern about Audio Performance

Check this out. I took it straight for the documentation:

The method Unity uses to load audio assets at runtime.

Decompress on load
Audio files will be decompressed as soon as they are loaded. Use this option for smaller compressed sounds to avoid the performance overhead of decompressing on the fly. Be aware that decompressing sounds on load will use about ten times more memory than keeping them compressed, so don't use this option for large files.

Compressed in memory
Keep sounds compressed in memory and decompress while playing. This option has a slight performance overhead (especially for Ogg/Vorbis compressed files) so only use it for bigger files where decompression on load would use a prohibitive amount of memory. Note that, due to technical limitations, this option will silently switch to Stream From Disc (see below) for Ogg Vorbis assets on platforms that use FMOD audio.

Stream from disc
Stream audio data directly from disc. The memory used by this option is typically a small fraction of the file size, so it is very useful for music or other very long tracks. For performance reasons, it is usually advisable to stream only one or two files from disc at a time but the number of streams that can comfortably be handled depends on the hardware.

Compression
Amount of Compression to be applied to a Compressed clip. Statistics about the file size can be seen under the slider. A good approach to tuning this value is to drag the slider to a place that leaves the playback "good enough" while keeping the file small enough for your distribution requirements.