Start with render distance
Render distance is the single biggest performance lever in the game. Players who grabbed the game from the LovelyCraft homepage get the same build discussed here. Dropping it one or two notches can double the frame rate on old phones, and you will barely notice while building. Find it in the game's graphics settings.
Trim the world
Giant worlds with thousands of placed blocks strain budget GPUs. Build compact, or split mega-projects across several worlds. Survival explorers should avoid generating endless new terrain in one session.
Phone hygiene
Close background apps before playing, keep 1 GB of free RAM, and restart the phone if the game stutters after long sessions. These three habits fix most crash and freeze issues too. The light 44 MB build from the download page is already kind to old hardware; these tweaks finish the job. More background on the build is on this site.