Slow iMac after 10.8.3 update

I posted a few dfays ago an as yet have no responeses from that post so here goes again.

When I restart to Windows (7) the startup chime chimes almost immediately but then a blank canvas screen comes on and the computer just sits there seemingly doing nothing for nearly a minute, then Windows starts and things look normal. When I go back to Mac OS the chime chimes again almost immediately but I get a black, blank screen for about 40 seconds before the Apple logo comes up and the wheel start spinning and the Mac starts up. Everything seems to be normal once it os going with the exception that once and a while I have to restart the computer again in ML to get the Dock to magnify. This all started after I updated to ML 10.8.3. Windows is on a partition made by Bootcamp Assistant to the tune of 40 GB. That leaves me with 250+ GB for ML. The iMac is an early 2009 320/4GB Ram and there are not many third party apps installed except the ones I have to install for Windows and some sites that require Adobe and Java to run, which are both up to date according to there sites. My question is, why does the computer do this suddenly after an upgrade to ML when it never did this before? Also then I restarted the computer in Recovery and verified and repaired the OS and then restarted the Mail app showed I was offline and I had to restart again to rectify the problem. Just seems like the upgrade did more harm than good!

I am getting very close to going back to SL, the last good OS Apple put out, where I had very few problems with any of this stuff. I really like some of the new stuff Lion and ML had to offer but the problems are getting to the point where it is not worth the effort. Suggestions would be appreciated.

C