Dramatic reduction in performance after adding RTC

[frankpintosr]

Better try to add desired lines to default OpenAuto Pro /boot/config.txt file:

# For more options and information see
# http://rpf.io/configtxt
# Some settings may impact device functionality. See link above for details

# uncomment if you get no picture on HDMI for a default "safe" mode
#hdmi_safe=1

# uncomment this if your display has a black border of unused pixels visible
# and your display can output without overscan
#disable_overscan=1

# uncomment the following to adjust overscan. Use positive numbers if console
# goes off screen, and negative if there is too much border
#overscan_left=16
#overscan_right=16
#overscan_top=16
#overscan_bottom=16

# uncomment to force a console size. By default it will be display's size minus
# overscan.
#framebuffer_width=1280
#framebuffer_height=720

# uncomment if hdmi display is not detected and composite is being output
#hdmi_force_hotplug=1

# uncomment to force a specific HDMI mode (this will force VGA)
#hdmi_group=1
#hdmi_mode=1

# uncomment to force a HDMI mode rather than DVI. This can make audio work in
# DMT (computer monitor) modes
#hdmi_drive=2

# uncomment to increase signal to HDMI, if you have interference, blanking, or
# no display
#config_hdmi_boost=4

# uncomment for composite PAL
#sdtv_mode=2

#uncomment to overclock the arm. 700 MHz is the default.
#arm_freq=800

# Uncomment some or all of these to enable the optional hardware interfaces
#dtparam=i2c_arm=on
#dtparam=i2s=on
#dtparam=spi=on

# Uncomment this to enable the lirc-rpi module
#dtoverlay=lirc-rpi

# Additional overlays and parameters are documented /boot/overlays/README

# Enable audio (loads snd_bcm2835)
dtparam=audio=off
#dtoverlay=vc4-kms-v3d
gpu_mem=256
dtoverlay=vc4-fkms-v3d
disable_splash=1

dtoverlay=i2c-rtc,ds3231                                                                                                              
dtparam=i2c_arm=off

That was the issue!  Once I added the following lines to /boot/config.txt performance went back to normal.  

gpu_mem=256
dtoverlay=vc4-fkms-v3d

After that test I deleted my config.txt, renamed my config.txt.backup to config.txt, added the two lines above, saved and rebooted.  I also looked at my process to get the RTC working and found I renamed the original config.txt and then created a new file called config.txt  It was a simple as changing the command line as shown below.

sudo mv /boot/config.txt /boot/config.txt.backup
to
sudo cp /boot/config.txt /boot/config.txt.backup