Not sure what you're doing there, but 5.12 uses less cpu & memory than 2.9x
Sure, 5.09 to 5.112 used more memory for large playlists, but that has been greatly optimized in 5.12.
If you want a Lite player, then either install the Lite version, or install Full, but uncheck whatever features/plugins you don't want in the installer options
"winamp 5.12 has nothing more than the old ones"
I beg to differ.
It's got hundreds of bugfixes (some critical) in: in_mp3, in_cdda, in_vorbis, in_mod, in_midi, in_wm, in_dshow, out_ds, out_wave, vis_avs, vis_milk, and more, a vastly improved media library (compared to the one in 2.9x), global title formatting, queued playback (far superior to that of wa3), and optional
support for: modern skins, video playback, cd ripping & burning, podcasts, etc etc, etc. Oh, and native M4A/AAC/AACPlus support :-p
"just look what happens if u shutdown the new winamp"
Maybe you just need to uncheck "look for new channels on exit" in:
Prefs > Media Library > Online Media > Modify Preferences ?