If you are getting noticable fps drop I do NOT recommend to use BetterSkies feature (deselect it in the MCPatcher).


To change the HD night sky to a lower resolution you have 2 options:
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A) rename the file "ornatestarsHD.png" to something else or delete it... and then rename the "ornatestarsLow.png" to "ornatestarsHD.png"

B) open the sky1.properties file in text editor (ie. Notepad++) and there change the ornatestarsHD to ornatestarsLow


But if you ask me... I find the Low resolution night sky ugly and in such case I would rather stick with default mc night sky and not use BetterSkies feature at all.