Hello fellow ZorinOS enjoyer,
i dual booted ZorinOS today and really enjoy it so far. The only downside:
its being quite laggy while watching videos.
Does anyone know why?
GPU, CPU, Drive useage is low and im using a SSD, i9 processor and a RTX3060TI with 3 Monitors. One with 75HZ, one with 144hz and the third with 60hz. The one with 144hz is also running in 4k.
Installed all the codecs and using nvidia driver 570
Thank you in advance dear friends!
Welcome to the Forum!
Because You are Dual-Booting:
Because of the Codecs:
ubuntu-restricted-extras?Because You are using a Nvidia Card:
sudo apt purge nvidia* to delete the current Nvidia Driver. Then type sudo apt install nvidia-driver-[Version-Number] nvidia-dkms-[Version-Number] to install the Driver again or install a different Version (like 550 or 535 for Example). Repeat this to test different Driver Versions.Then You could try it with a newer Kernel. Instructions and Guides for this, You can find there:
Another Thing: Is in Your Display Settings Fractional Scaling active? If yes, try it with turning it off.
You wrote it is while watching Video's. Is it in a Browser or in a Program? Please name it. And is this the Flatpak Version or the APT Version of the Program. If it is the Flatpak Version, You could try it with the APT Version instead if available.
Considering another member who posted about lag issues with Wayland, I am willing to bet, if the OP here switches to Zorin Desktop on X11/Xorg, it alone will fix the problem. 
We will see.
I have done a clean install of ZorinOS, just for the sake of it as i have not done much to it anyways. So far, its runs really good.
But i'll answer the questions anyways, it would be rude not to!
Are Secure Boot and Fast Boot in BIOS disabled? Yes sir, both are disabled
Is Fast Start-Up in Windows disabled? Yes sir, that too!
Is Your BIOS in UEFI or Legacy Mode? UEFI
What Tool did You use to create the bootable USB Stick? Rufus via Windows
What Installation Option did You choose (Install Zorin alongside Windows, Something else)? I used my second SSD, which was completly empty. Created a EFI partition with around a 1GB of space and the rest for "/"
Did You installed the Codecs of the Gnome Software Center (on the Startpage scroll all the Way down to the End and click on the ''Codecs'' Button) Yes, i did. I assume that caused the problems? As you may have noticed, im quite new but willing to learn!
Did You installed ubuntu-restricted-extras? Yes, i did.
Did You installed VLC? Was preinstalled, so i would say no.
Did You installed ffmpeg? Yes i did.
Is Your System run in X11/Xorg or Wayland? You can check that in Settings>About. When it is in Wayland, switch to Xorg. To do that, go to the Login Screen (not the Lock Screen). Simply reboot for that. On the Login screen, click on Your Profile so that the Password Field appears. It has to be appeared. when it is appeared, you should see a Gear Icon in the bottom right Corner. Click on it and choose the Option ''Zorin Desktop on Xorg'' and then log in and test it. Shows X11, tried to use wayland before, but i heard that it causes issues and i have noticed that too.
You wrote that You use the 570 Driver. Did You tried it with a Reinstall or the Installation of a different Version? To do that, first type sudo apt purge nvidia* to delete the current Nvidia Driver. Then type sudo apt install nvidia-driver-[Version-Number] nvidia-dkms-[Version-Number] to install the Driver again or install a different Version (like 550 or 535 for Example). Repeat this to test different Driver Versions. Tried different drivers, sadly without any changes to the problem.
EDIT: I'll try to reproduce the steps i did before. Whatever i do, i'll write it down to pin point the exact cause. That's probably the best thing to do in this situation, so no need to assist me on the matter as this would be finding the needles in a stack of hay. I'm sorry for bothering, i should have done that before.
Thank you for helping me 
I really appreciate it!
(Please pardon my english, as it is not my first language!)
Greetings,
Moe
Not neccessary. English isn't my first Language, too. And Your's reads and sounds way better than mine, hahaha!
When it now works, that is what matters. To take some Points of You for some Details for the Future:
Rufus is a good Tool. I used it in the Past when I Windows was on my Machine, too. And there is one Setting/Option what is really nice to have. Because Your BIOs is in UEFI, it would be good to use GPT for the Partition Sheme for creating the USB Stick. You can set up it in Rufus her (the red marked Area):
Could, but don't have to. This ''Laggy'' Issues can be a bit difficult to adress. Beneath Codecs or Wayland/X11 another Thing could be if You have in the Display Settings Fractional Scaling active. Or maybe a newer Kernel could help.
That is okay. Because You have a Nvidia Card it is at the Moment better to use X11 on Zorin.
No Sorry needed. We all started at one Point; that is normal. And when You look for an Answer and don't find the right Thing for You or it simply doesn't work, it is totally fine to ask here. The Forum exists for this. And zorin is adressed to new Users. and when You as a new User have an Issue and can't get it solved, it is fine to ask. And like it already said: When it works now, that is what matters.
Update:
Well, im quite embarassed. I had it happen again today. Was watching 2 streams on Twitch and started watching a YouTube Video in 4k (TikTok brain i guess?).
So, i thought to myself: Do i have hardware acceleration on?
And nope. It was off. Enabled it, restarted Brave and the overall experience is MUCH smoother now.
Such a "meaningless" thing made my head hurt haha.
Just wanted to give an update here, in case someone else is looking for the issue!
