Yes, I also noticed lags, when changing wallpapers (via holding your finger on Home Screen and selecting Wallpapers).
I did my first ever Lineage OS install recently. I used lineage-16.0-20210608-UNOFFICIAL-pollux_windy.zip build and followed all the instructions from https://forum.xda-developers.com/t/...-or-wifi-any-version-to-android-9-pie.3392831 for Sony Xperia Tablet Z Wi-Fi.
Everything works fine, including the camera and 5GHz Wi-Fi network. The only thing that bothered me, were lags while setting / selecting / scrolling default wallpapers. I noticed they were not scaling (or fitting) nicely, too. The workaround, was to create my own squared wallpapers (1920x1920), so that they match the native width of the display while in horizontal or vertical position.
Now I have a few custom wallpapers in the Gallery. They fit much better than the stock ones. You can set them without lags, if you do it via the Settings -> Display -> Advanced -> Wallpaper -> Gallery -> Select item -> SET WALLPEPER. It's a lot of tapping, but going directly to Gallery bypasses displaying stock wallpapers, hence there are no lags.
UPDATE: The fastest way is to select Gallery from your Home Screen -> Choose a picture and tap on options (...) -> Set picture as -> SET WALLPAPER. It sets both Home & lock screen backgrounds at once.
- Boot : Ok - GApps : OpenGApps Nano Ok - FOTA Recovery : Ok (see below) - WiFi : Ok (real SONY MAC address) - Bluetooth : Ok (real SONY MAC address) - WiFi Hotspot : Ok (2.4GHz only) - RIL - Phone - Data : Ok - GPS : Ok - Camera : Ok - Camcorder : Ok - MicroSD : Ok - Accelerometer : Ok - Compass : Ok - Gyroscope : Ok - AOSP sensors : Ok - FM Radio : Work In Progress - Microphone : Ok - Audio & external audio : Ok - Bluetooth audio : Ok - NFC : Ok - Kernel : Ok, Updating frequently - Graphics : Ok - 3D Rendering : Ok - Clock : Ok - Offline Charging : Ok - SEPolicies : Work In Progress