I’m currently using an OpenWrt snapshot and perfomance is the same or in some cases better, since there’s less processes running and more bugs have been fixed. Plus all of the packages are up to date.
If you install an OpenWrt snapshot then it won’t have any UI until you install LuCI. Although you should be able to customise the packages via the firmware selector so that it comes with LuCI, Adguard Home, DDNS and Attended Sysupgrade.
Packages
adguardhome bind-host bridger base-files busybox ca-bundle ca-certificates curl dnsmasq dropbear e2fsprogs f2fsck firewall4 fstools kmod-crypto-hw-safexcel kmod-gpio-button-hotplug kmod-leds-gpio kmod-mt7915e kmod-mt7986-firmware kmod-nft-offload kmod-usb3 libc libgcc libustream-mbedtls logd luci luci-app-attendedsysupgrade luci-app-ddns mkf2fs mt7986-wo-firmware mtd netifd nftables odhcp6c odhcpd-ipv6only opkg ppp ppp-mod-pppoe procd procd-seccomp procd-ujail uboot-envtools uci uclient-fetch urandom-seed urngd wpad-basic-mbedtls
You won’t be able to setup the router wirelessly though, since WiFi is disabled by default.
Only ever flash the Sysupgrade image. Flashing anything else can cause issues if you mess something up.
And when setting up Adguard Home be sure to listen on all interfaces, otherwise the service might fail to start and web pages won’t load.