The screenshots don't reveal much. I don't know why. The difference is obvious. I've shown it to people here and they agree. Anyone reading this will have to take my word.
Google directed me toward a lot of articles about people having font problems in 10.6, though interestingly I didn't find one of them who had problems only when they hit 10.6.8. Usually it was 10.6.7 or earlier, and their complaints had to do with blurry fonts. Mine aren't blurry, they seem too bright and jagged like there's no smoothing at all. The setting in System Prefences>Appearance doesn't change anything. Some articles suggested changing the smoothing and empty font caches through the Terminal, which I did and it didn't have any effect.
http://osxdaily.com/2015/01/08/clear-font-caches-databases-mac-os-x/http://osxdaily.com/2010/02/18/change-font-smoothing-settings/http://osxdaily.com/2012/06/09/mac-screen-blurry-optimize-troubleshoot-font-smoothing-os-x/I even tried TinkerTool to change smoothing and system fonts but that didn't work.
Many people have had problems with Helvetica and Helvetica Neue, as well as OpenType fonts and Postscript fonts. Some even have problems with the latest OS. That's not very impressive. In Windows 8.1, on a Dell monitor, the fonts really look nice. Even on Ubuntu. What's the problem with Apple? Why can't they get the basics right? To me that's one of the most important things in an operating system. If fonts hurt my eyes, I can't use the OS.
Interesting that someone mentioned that the default setting for the monitor is supposed to be the highest one, which on my imac is 1440x900. That's too small for me. I always use 1152x720. I didn't follow that advice when I set up my parents Dell either. It took me a long time to find a suitable medium between too small and too large. I don't know whom these default settings are for.
I wonder if the graphics drivers in the ATI card is causing the problem, since that was causing kernel panics in Firefox. I doubt the graphics card is involved in rendering fonts.
I continue to use Beyond Compare, a fine program, to analyze which files have changed from 10.6.7 to 10.6.8. I'm worried that the culprit will be some obscure file which I shouldn't change, like Ruby or Pearl or some framework or something in the Core system files. Quartz maybe. I noticed some Thunderbolt files which I could probably delete since I don't have a Thunderbolt monitor. I know better than to start deleting just to experiment. There are too many deep files whose purpose is unknown to me.
ETA: Interesting that in recent OS Apple gave up on Helvetica altogether as a system font.
