Amazing Slow Downer contains a number of different slow down algorithms. In general, the higher the quality is, the more processor usage will be required and thus will drain the battery faster.

You may select a lower audio quality setting which allows for longer battery life or if using newer devices you may select the "Very High 1" quality setting for better sound quality. The best sound quality is when you select "Very High 2" quality, because of it preserving transients this makes it especially good for percussive instrument such as drums, piano, guitar etc.

For classical non-percussive music, the "High" quality setting may actually be the best.

If the audio contains speech only, try the "Speech Only" quality setting.

You may also enable/disable the audio processing and select whether to slow down in stereo or mono. Stereo processing requires more processor usage and may drain the battery faster. For longest battery life, use the lowest possible setting.