If you’re using Foobar2k, a great free music player from the creator of Winamp, you probably noticed that its folder is getting bigger and bigger over time.
That is cause by wavecache.db in Foobar2000 root folder. This file is used by Waveform Seekbar plugin to store its data.
You may delete that file from drive or select MENU->Library->Waveform Seekbar->Compact Wavefrom Database from the interface. That has to be done manually once in a while. Better yet, just remove the Waveform Seekbar from Menu->Preferences->Components or delete/rename foo_waveform_seekbar.dll in the Foobar2000 components folder. That plugin is quite useless anyway.