My zorin installation is giving problems with speed and with theming

[SignorCastello]

I installed zorin os 6 months ago, and now I have problems:
until 3 minutes after it's booted it's slow, but waiting 5 mins and the issue fixes, the process taking up more cpu is xorg (and something like that)
and I have another issue, with themes. When I switch to light theme this issues appears:

(currently writing from 5.13.0-30-generic, since the other one MAYBE is slower...idk)
How to solve this??

[Aravisian]

@SignorCastello

When I switch to light theme this issues appears:

What issue? I am not able to see anything wrong there. You have a Blue accent selected with dark background.
You may try selecting the tab for Other and selecting the Zorin Theme you want directly. For example, Zorin-blue-light...

@SignorCastello

until 3 minutes after it's booted it's slow, but waiting 5 mins and the issue fixes, the process taking up more cpu is xorg (and something like that)

Something is creating an initialization error. Can you edit grub

sudo nano /etc/default/grub

Change GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" to GRUB_CMDLINE_LINUX_DEFAULT=""
ctrl+x to exit, then the y (or s) to say yes to save, then the enter key.
Now run sudo update-grub
Reboot and monitor the messages, looking for errors or failures to initialize.