I have been daily driving Zorin OS over two months, here is my laptop specs:
OS: Zorin OS 16.2 x86_64
Kernel: 5.15.0-67-generic
CPU: Intel i5-8250U (8) @ 3.400GHz
GPU: Intel UHD Graphics 620
Memory: 8GiB
Disk: 256GB NVMe
At first I was pleasantly impressed by the speed and performance of the OS, then I notice that the system starts getting slow and glichy over time. After troubleshooting and testing, I saw that the swap partition gets fulled up pretty quickly from daily use, mainly heavy web browsing, when that happens, the CPU spikes and the system start struggling finding spare memory.
The swap space is on nvme m.2 drive, I don't notice performance issue when the system use the swap space, but when that space fills up, then I notice the performance degradation.
So, I started optimizing the OS, removing unwanted apps, disabling unnecessary services at startup (specially gnome-software). I added another 2 Gb swap file (default swap partition size on Zorin OS is 1Gb), adjusted the system swapiness and cache pressure, but the problem persisted, even the extra 2Gb swap file get filled up quickly and system start getting slow over time, especially because I don't restart my laptop that much(that wont change).
I believe this issue is more prevalent on laptop sub 8 Gb RAM, I started to looking into zram and zswap. To over simplify, zram takes a portion of ram and tuned into swap space with compression 2:1, zswap is kinda similar (ratio 3:1) but spill over into a swap disk space when the ram portion gets filled up.
I tested fedora kde spin which has zram by default, the portion of swap ram gets filled up quickly since there is swap content that don't compress well. The same issue happens with zram as well, the system gets slow and unresponsive over time.
I setup zswap on Zorin OS, zswap is part of the Linux kernel by default, I was greatly impressed by the improvement in performance and the stability of the system. I tested opening 80+ tabs (dynamic websites) on brave browser and opening a couple of tabs on firefox at same time, apart from a spike in CPU (not even the CPU fan ran), system stayed stable and responsive.
I also notice the swap disk space don't fill up as much, just a small spill over over from RAM compressed swap to disk swap space.
Overall, I highly recommend activating zswap for improving system performance, specially for laptop with a limited RAM size.
Since Zorin OS strive on reviving old laptops (mine 4 years old) and provide excellent user experience, this should be at least an option on the OS installation wizard or adjusting the default swap partition size according to RAM size. (Windows OS default 8Gb RAM ≈ 8Gb page file size).
P.S. I linked to relevant articles and tutorials through out the post.