I learned to never assume something while troubleshooting and always check for fact instead 
I’m as lost as y’all on where to go from here.
I’m starting to think it is related to the WM instead of DE…
BTW: How much RAM does your laptop have, maybe it’s related to that?
Like in you use x amount of RAM for the OS+Applications open and then the system needs a bit more to perform the move of the window etc, thus starts to use the swap.
(It could also be the speed of your HD in that case)
Well, it seems I made an error in my original post. Installing the game I could easiest get on short notice, it runs perfectly well. Really well actually, no stuttering at all. Checking back to Firefox the issue is gone, but as soon as the game closed the issue returned, so bad I had to force reboot my machine. This made me audibly react. I’m very, very confused now. My laptop has 16 gigs of RAM.
Lets try to eliminate this possibility, by asking if you notice heavy HD activity while your system feels slow…
I don’t, no.
This is a very weird problem that is making my grey hairs even grayer 
/me Lets step aside from this problem for a while and let our brains work in background on it 
could you please install sysstat
pamac install sysstat
and show the output of
iostat -x
It will show the cpu and disk activity since your last boot and make a report of it
when you run it a second time it will show the activities since the last report.
It will also answers @TriMoon question about the diskusage
Linux 5.9.11-3-MANJARO (manjaro) 12/11/2020 _x86_64_ (12 CPU)
avg-cpu: %user %nice %system %iowait %steal %idle
5.01 0.01 2.48 0.01 0.00 92.49
Device r/s rkB/s rrqm/s %rrqm r_await rareq-sz w/s wkB/s wrqm/s %wrqm w_await wareq-sz d/s dkB/s drqm/s %drqm d_await dareq-sz f/s f_await aqu-sz %util
loop0 0.00 0.00 0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
nvme0n1 9.03 339.09 3.43 27.53 0.12 37.57 4.24 81.81 2.97 41.20 0.16 19.28 0.00 0.00 0.00 0.00 0.00 0.00 0.31 0.30 0.00 0.38Also nothing really out of the ordinary here so all seems well hardware related as far I can tell by these outputs.
@TriMoon is still thinken (using his brains for ones 
) so perhaps he or @SDN can think of anything else.
I need to step back for a moment also
I strongly believe that this is a firmware issue (or maybe pulseaudio getting buffer underrun). You know that System76 is the one that develop Pop!OS, a Ubuntu based distro. Cmiiw, Ubuntu have more “stable” firmware management than rolling release type distro, like Manjaro. But I’ve been wrong before, so @amanda can wait for the next firmware update or back to Ubuntu (or Pop!OS as the laptop manufacturer recommend), or pray that someone else with the same laptop can troubleshoot this issue.
PS:
I’ve googled a bit and haven’t found any similar problem on Arch based system with this particular laptops though.
(Oh, I really hope I don’t get banned for ‘advertising’ other distro in here) 
Well to rule out pulse audio issues he can just stop the service and check if the issue persist or not
systemctl --user stop pulseaudio.socket
systemctl --user stop pulseaudio.service
or
sudo systemctl stop pulseaudio.socket
sudo systemctl stop pulseaudio.service
should handle that
Still having the problem, sadly.
@amanda if you still wanted to find out what causing that lag on your laptop, you can reproduce the lag (playing the game, turn it off and playing a video) and then post the last 2 page from this command:
sudo journalctl --since “20 min ago”
PS:
It may expose unnecessary info from your laptop, but mostly are safe (I think).
-- Logs begin at Fri 2020-12-11 02:53:38 EST, end at Fri 2020-12-11 20:46:40 EST. --
Dec 11 20:43:04 manjaro kernel: Freezing user space processes ... (elapsed 0.001 seconds) done.
Dec 11 20:43:04 manjaro kernel: OOM killer disabled.
Dec 11 20:43:04 manjaro kernel: Freezing remaining freezable tasks ... (elapsed 0.000 seconds) done.
Dec 11 20:43:04 manjaro kernel: printk: Suspending console(s) (use no_console_suspend to debug)
Dec 11 20:43:04 manjaro kernel: ACPI: EC: interrupt blocked
Dec 11 20:43:04 manjaro kernel: ACPI: Preparing to enter system sleep state S3
Dec 11 20:43:04 manjaro kernel: ACPI: EC: event blocked
Dec 11 20:43:04 manjaro kernel: ACPI: EC: EC stopped
Dec 11 20:43:04 manjaro kernel: PM: Saving platform NVS memory
Dec 11 20:43:04 manjaro kernel: Disabling non-boot CPUs ...
Dec 11 20:43:04 manjaro kernel: smpboot: CPU 1 is now offline
Dec 11 20:43:04 manjaro kernel: smpboot: CPU 2 is now offline
Dec 11 20:43:04 manjaro kernel: smpboot: CPU 3 is now offline
Dec 11 20:43:04 manjaro kernel: smpboot: CPU 4 is now offline
Dec 11 20:43:04 manjaro kernel: smpboot: CPU 5 is now offline
Dec 11 20:43:04 manjaro kernel: smpboot: CPU 6 is now offline
Dec 11 20:43:04 manjaro kernel: smpboot: CPU 7 is now offline
Dec 11 20:43:04 manjaro kernel: smpboot: CPU 8 is now offline
Dec 11 20:43:04 manjaro kernel: smpboot: CPU 9 is now offline
Dec 11 20:43:04 manjaro kernel: smpboot: CPU 10 is now offline
Dec 11 20:43:04 manjaro kernel: smpboot: CPU 11 is now offline
Dec 11 20:43:04 manjaro kernel: ACPI: Low-level resume complete
Dec 11 20:43:04 manjaro kernel: ACPI: EC: EC started
Dec 11 20:43:04 manjaro kernel: PM: Restoring platform NVS memory
Dec 11 20:43:04 manjaro kernel: LVT offset 0 assigned for vector 0x400
Dec 11 20:43:04 manjaro kernel: Enabling non-boot CPUs ...
Dec 11 20:43:04 manjaro kernel: x86: Booting SMP configuration:
Dec 11 20:43:04 manjaro kernel: smpboot: Booting Node 0 Processor 1 APIC 0x1
Dec 11 20:43:04 manjaro kernel: microcode: CPU1: patch_level=0x08701013
Dec 11 20:43:04 manjaro kernel: CPU1 is up
Dec 11 20:43:04 manjaro kernel: smpboot: Booting Node 0 Processor 2 APIC 0x2
Dec 11 20:43:04 manjaro kernel: microcode: CPU2: patch_level=0x08701013
Dec 11 20:43:04 manjaro kernel: CPU2 is up
Dec 11 20:43:04 manjaro kernel: smpboot: Booting Node 0 Processor 3 APIC 0x3
Dec 11 20:43:04 manjaro kernel: microcode: CPU3: patch_level=0x08701013
Dec 11 20:43:04 manjaro kernel: CPU3 is up
Dec 11 20:43:04 manjaro kernel: smpboot: Booting Node 0 Processor 4 APIC 0x4
Dec 11 20:43:04 manjaro kernel: microcode: CPU4: patch_level=0x08701013
Dec 11 20:43:04 manjaro kernel: CPU4 is up
Dec 11 20:43:04 manjaro kernel: smpboot: Booting Node 0 Processor 5 APIC 0x5
Dec 11 20:43:04 manjaro kernel: microcode: CPU5: patch_level=0x08701013
Dec 11 20:43:04 manjaro kernel: CPU5 is up
Dec 11 20:43:04 manjaro kernel: smpboot: Booting Node 0 Processor 6 APIC 0x8
Dec 11 20:43:04 manjaro kernel: microcode: CPU6: patch_level=0x08701013
Dec 11 20:43:04 manjaro kernel: CPU6 is up
Dec 11 20:43:04 manjaro kernel: smpboot: Booting Node 0 Processor 7 APIC 0x9
Dec 11 20:43:04 manjaro kernel: microcode: CPU7: patch_level=0x08701013
Dec 11 20:43:04 manjaro kernel: CPU7 is up
lines 1-49
-- Logs begin at Fri 2020-12-11 02:53:38 EST, end at Fri 2020-12-11 20:46:40 EST. --
Dec 11 20:43:04 manjaro kernel: Freezing user space processes ... (elapsed 0.001 seconds) done.
Dec 11 20:43:04 manjaro kernel: OOM killer disabled.
Dec 11 20:43:04 manjaro kernel: Freezing remaining freezable tasks ... (elapsed 0.000 seconds) done.
Dec 11 20:43:04 manjaro kernel: printk: Suspending console(s) (use no_console_suspend to debug)
Dec 11 20:43:04 manjaro kernel: ACPI: EC: interrupt blocked
Dec 11 20:43:04 manjaro kernel: ACPI: Preparing to enter system sleep state S3
Dec 11 20:43:04 manjaro kernel: ACPI: EC: event blocked
Dec 11 20:43:04 manjaro kernel: ACPI: EC: EC stopped
Dec 11 20:43:04 manjaro kernel: PM: Saving platform NVS memory
Dec 11 20:43:04 manjaro kernel: Disabling non-boot CPUs ...
Dec 11 20:43:04 manjaro kernel: smpboot: CPU 1 is now offline
Dec 11 20:43:04 manjaro kernel: smpboot: CPU 2 is now offline
Dec 11 20:43:04 manjaro kernel: smpboot: CPU 3 is now offline
Dec 11 20:43:04 manjaro kernel: smpboot: CPU 4 is now offline
Dec 11 20:43:04 manjaro kernel: smpboot: CPU 5 is now offline
Dec 11 20:43:04 manjaro kernel: smpboot: CPU 6 is now offline
Dec 11 20:43:04 manjaro kernel: smpboot: CPU 7 is now offline
Dec 11 20:43:04 manjaro kernel: smpboot: CPU 8 is now offline
Dec 11 20:43:04 manjaro kernel: smpboot: CPU 9 is now offline
Dec 11 20:43:04 manjaro kernel: smpboot: CPU 10 is now offline
Dec 11 20:43:04 manjaro kernel: smpboot: CPU 11 is now offline
Dec 11 20:43:04 manjaro kernel: ACPI: Low-level resume complete
Dec 11 20:43:04 manjaro kernel: ACPI: EC: EC started
Dec 11 20:43:04 manjaro kernel: PM: Restoring platform NVS memory
Dec 11 20:43:04 manjaro kernel: LVT offset 0 assigned for vector 0x400
Dec 11 20:43:04 manjaro kernel: Enabling non-boot CPUs ...
Dec 11 20:43:04 manjaro kernel: x86: Booting SMP configuration:
Dec 11 20:43:04 manjaro kernel: smpboot: Booting Node 0 Processor 1 APIC 0x1
Dec 11 20:43:04 manjaro kernel: microcode: CPU1: patch_level=0x08701013
Dec 11 20:43:04 manjaro kernel: CPU1 is up
Dec 11 20:43:04 manjaro kernel: smpboot: Booting Node 0 Processor 2 APIC 0x2
Dec 11 20:43:04 manjaro kernel: microcode: CPU2: patch_level=0x08701013
Dec 11 20:43:04 manjaro kernel: CPU2 is up
Dec 11 20:43:04 manjaro kernel: smpboot: Booting Node 0 Processor 3 APIC 0x3
Dec 11 20:43:04 manjaro kernel: microcode: CPU3: patch_level=0x08701013
Dec 11 20:43:04 manjaro kernel: CPU3 is up
Dec 11 20:43:04 manjaro kernel: smpboot: Booting Node 0 Processor 4 APIC 0x4
Dec 11 20:43:04 manjaro kernel: microcode: CPU4: patch_level=0x08701013
Dec 11 20:43:04 manjaro kernel: CPU4 is up
Dec 11 20:43:04 manjaro kernel: smpboot: Booting Node 0 Processor 5 APIC 0x5
Dec 11 20:43:04 manjaro kernel: microcode: CPU5: patch_level=0x08701013
Dec 11 20:43:04 manjaro kernel: CPU5 is up
Dec 11 20:43:04 manjaro kernel: smpboot: Booting Node 0 Processor 6 APIC 0x8
Dec 11 20:43:04 manjaro kernel: microcode: CPU6: patch_level=0x08701013
Dec 11 20:43:04 manjaro kernel: CPU6 is up
Dec 11 20:43:04 manjaro kernel: smpboot: Booting Node 0 Processor 7 APIC 0x9Accidentally replied to the thread and not you, oops.
Is that the last page from the journactl output after you play a game? Did you press “End” key after executing journalctl command?
I don’t really understand technically, I’m not technician so I might be wrong, but looks like your CPU cores went to a sleep mode in a middle of doing something. Your CPU lost power. Hmm, Isn’t that kinda odd? Or is it a feature?
I’m still suspecting this is a firmware issue related to power management but can you try different kernel. Use LTS kernel 5.4.
PS:
Quickly after BIOS boot press Esc to show Manjaro GRUB and choose kernel 5.4 (after you install it). The GRUB might not show up if you don’t do that and automatically select the latest kernel available.
Edit:
Oh, I forgot something. When your laptop is laggy, please execute cpupower frequency-info and post the output. I’ve found some info about gnome being sluggish after waking up from sleep mode.
Edit again:
While checking cpupower, please open nvidia xserver setting, quickly go to power mizer and make sure it show that your gpu performance is at max level before going down. Just to make sure it’s not gpu fault.
Another Edit:
This post might be related: Issues with mouse stutter
The OP use LTS kernel, but I suggest you still try it as there is a chance that these are different issues. I hope Manjaro devs take notice of these reports.
You seem to have pasted the same info 2x with a blank page in-between…
But anyhow this part looks abnormal to me:
Because it shows that you laptop is waking up from sleep right after/at same time it went to sleep: Same timestamps “20:43:04”
This should never be the case…
Also imho it should have said ACPI: Low-level sleep complete instead of ACPI: Low-level resume complete, but that might have been a wrong text in that module who knows…
Most probable cause would be because those events all fired at same split second and the messages are shown interleaved with each other instead of in sequence of action.
So my conclusion is:
There is some serious problem with Power Management.
We just have to figure out if it is in software or hardware…
Could you check your BIOS settings wrt APM (Advanced Power Managment)?
PS, The thread started with a cold dive in water, and we forgot to say:
Hi and welcome to the forum 
Please see: How to provide good information
Although we got most info already, we still have no idea about what brand and model your laptop is, which might be related
Yes we know
That’s what I initially thought, which is why I asked to modify the kernel line in Grub.
The strange part is when those lines have been set what shows in the log, should not occur
Ahh that must have skipped my mind, that’s why it’s important to have all relevant info in first post 