I set Winamp to play the same song (with repeat enabled) for more than 11 hours of uptime, and observed its private memory getting bigger and bigger over time.
https://i.imgur.com/9XESWoD.png
As shown on the diagnostic screenshot, Winamp is leaking more memory the longer it is run for.
This is obviously unusual memory usage for a music player... (WMP doesn't have this issue.)
Shortly after 12 hours and 15 minutes of uptime, Winamp has allocated over 1GB of private memory.
I am running a clean install of the currently latest official Winamp (version 5.8 beta, build 3660) on Windows 10 (x64) system.
If there is anything else I can do to help solve this issue, let me know
Another report I found, possibly pointing out the same issue:
http://forums.winamp.com/showthread.php?t=455342