nfoav8or, There was no big difference in efi strings. My previous one was working just great since i installed the system. I was also injecting graphic strings via dsdt, working great, so completely removed device-properties from com.apple.boot. So i am a bit unsure here if it was new string from efistudio or reinstalling 10.5.6 update. Lots of people were complaining about mouse lags in iT/QT with nvidia 8xxx serie but definitely graphic drivers are not broken. Re-installing the update and trying with new string should fix the issue. Worked for me.

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