Until 2 weeks ago I also used 2.3.6 on my Galaxy S plus. A year ago, 2.3.3.
2.3.6 was faster, but the more I used it the more curious was the behavior.
Sometimes it was not possible to quickly make a call. When I pressed the green telephone receiver icon, nothing happened. Only after about 30 seconds, the dial image was displayed and I could make calls.
I think it was due to modern apps, with simply overstrained the gingerbread system....
Currently I use the ADC team CyanogenMod 11.0 release and am very happy with it.