[CentOS] Clunky Xorg with latest 6.7 upgrade?

Is it just me or does Xorg/Gnome seem slow and clunky to any other
desktop users once the 6.7 upgrade is done?

$ uname -a
Linux CentOS501.homegroannetwork 2.6.32-573.1.1.el6.x86_64 #1 SMP
  Sat Jul 25 17:05:50 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

$ cat /etc/centos-release 
CentOS release 6.7 (Final)

Top shows
  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
32160 root      20   0  259m 104m  22m R 76.5  1.3 559:07.79 Xorg
23391 hardtolo  20   0 6293m 215m  26m S 16.9  2.7  21:49.86 java
.
.
.
And several instances of Xorg (one per user in addition to the shown
root instance), java, FF, soffice.bin, a plugin-container for FF, ... 

Using stock Gnome Desktop with three active X sessions, 6 desktops for
two users, multiple FF instances with multiple tabs.

6-core AMD 3200PR with ...
$ free
             total       used       free     shared    buffers    cached
Mem:       8057856    5285484    2772372      34136     298992   1883828
-/+ buffers/cache:    3102664    4955192 
Swap:     14352376          0   14352376

First caught my attention as *usually* FF is the hog, although I have
seen Xorg bee the hog aoccasionally in the past.

What next caught me is when using Ksnapshot to select a region of the
screen the "window" no longer keeps up with my mouse movements, but lags
and is "jerky".

I have no custom xorg config, but have commented out the FF startup
in /etc/X11/xinit/Xclients:
# Argh! Nothing good is installed. Fall back to twm
{
    # gosh, neither fvwm95 nor fvwm2 is available; 
    # fall back to failsafe settings
    [ -x /usr/bin/xsetroot ] && /usr/bin/xsetroot -solid '#222E45'

    if [ -x /usr/bin/xclock ] ; then
	/usr/bin/xclock -geometry 100x100-5+5 &
    elif [ -x /usr/bin/xclock ] ; then
	/usr/bin/xclock -geometry 100x100-5+5 &
    fi
    if [ -x /usr/bin/xterm ] ; then
        /usr/bin/xterm -geometry 80x50-50+150 &
    fi
# Commented out firefox stuff.
#    if [ -x /usr/bin/firefox -a -f /usr/share/doc/HTML/index.html ];
then
#	/usr/bin/firefox /usr/share/doc/HTML/index.html &
#    fi
    if [ -x /usr/bin/twm ] ; then
	exec /usr/bin/twm
    fi
}

As a starting point I did (wrapping - I tried to clean a bit)
$ ps -ef|grep '32160\|32155\|11398'
root       841 11398  0 Aug12 ? 00:00:00 /usr/libexec/gdm-simple-slave
           --display-id /org/gnome/DisplayManager/Display3
root     11398     1  0 Aug12 ? 00:00:00 /usr/sbin/gdm-binary -nodaemon
root     11461 11398  0 Aug12 ? 00:00:00 /usr/libexec/gdm-simple-slave
           --display-id /org/gnome/DisplayManager/Display1
500      24891  1441  0 17:39 pts/42 00:00:00 grep 32160\|32155\|11398
root     32155 11398  0 Aug12 ? 00:00:00 /usr/libexec/gdm-simple-slave
         --display-id /org/gnome/DisplayManager/Display2
root     32160 32155 26 Aug12 tty7 09:33:09 /usr/bin/Xorg :1 -br
        -verbose -audit 4 auth /var/run/gdm/auth-for-gdm-4U2Ps1/database
          -nolisten tcp
root     32221 32155  0 Aug12 ? 00:00:00 pam: gdm-password

If no one else is seeing this sort of "slowdown" and has any clues where
to start looking I'd appreciate hearing your suggestions.

TIA for any thoughts,
Bill