Contacts and Mail: iMac upgrade perfect! MacBook Pro? kind of disastrous

Question

Hello everybody.  Seeking a bit of guidance.  First, what I did:
iMac: I downloaded and installed the Mountain Lion upgrade.  It worked flawlessly.  I haven't discovered any issues at all.  I was thrilled.
MacBook Pro:  I downloaded and installed the Mountain Lion upgrade.  I'm having very big problems with Mail and Contacts, and moderately big problems in some other areas.
Contacts - Despite logging in to iCloud in System Preferences and confirming all options to be enabled, Contacts will not load. It takes a long time to open, with a spnning ball for about a minute and a half or so, and then nothing happens.  I deselected Contacts in System Preferences and then reenabled it.  This didn't help.  I then signed out of iCloud altogether (opting to delete anything that might be kept locally on the machine) and then logged back in.  This didn't help.  I then went into Contact preferences, and disabled and then reenabled my iCloud account.  This didn't help.  I rebooted twice.  This didn't help.  I repaired permissions.  This didn't help.   I shut it down for 8 hours because I was about to destroy it with a hammer at that point.    This didn't help. 
Mail issue #1 - Mail takes forever (okay, about 2 minutes to be more accurate) to load.  My inbox loads correctly (verified with my iOS devices and my iMac) as well as other mailboxes.  However, I can't switch between mailboxes without the spinning ball taking over.  The application becomes unresponsive and has has to be forced to quit.  For example, when I switch between inbox and sent mail, the application becomes useless and just hangs.
Mail issue #2 - Mail is no longer completing addresses when I attempt to create a new email.  I am accustomed to Mail giving me a dropdown list to choose from after I type a few characters.  During my efforts to troubleshoot Mail last night, I would type a few letters and in the middle of typing the address, Mail would freeze up and not allow me to continue typing.  The "processing" spinning grey icon on the right side of the address entry box would spin and spin and spin like it was trying to find my address options, but eventually would just give up after about two minutes, at which point it would "release" and allow me to cotinue manually typing the address.  I'm not sure exactly how that works, i.e. does that information come from history in Mail or from the Contacts app, but for whatever reason, it's not working.
System Preferences - Takes a long time to open, and then an equally long time to close.  More spinning blue wheel time. 
I hope I explained everything clearly.  I wanted to make sure that if I'm asking for help from the community that I gave as much detail about the problems and what actions I have taken.
Thanks in advance to anybody who can offer any guidance.
Richard

Answer 1

You are definitely not alone. Have exactly the same issues on my MacBook Pro (early 2011 model) with 8GB RAM and 200 GB plus space on my HD remaining. Thought it was because a lot of apps were open but have the same problem when only running Mail plus, of course, some stuff that runs in the background all the time. But nowhere near the limit.
After upgrading yesterday Mail did a correct update of the database and was working OK the problem started this morning. One thing I noticed was that with Mail running (not properly but running) I used the send web page feature in Safari and noticed that in the dock the Mail app was loaded again and I seemed to have it running twice.
A new message window opened with the content filled but trying to enter an email address produced the spinning beach ball for like a minute and with every keystroke. Finally force quit and now it seems to hang each time.
Restarted the Mac a number of times without result.