Phone hangs and lags: how to fix

• Restart the phone; do it weekly.
• Keep at least 15% of storage free.
• Remove apps you never use and clear the cache of heavy ones.
• Update the apps and the system software.
• Turn off animations in Developer options if the phone is old.
• Back up and do a factory reset as the last option.

A phone that heats up and lags together may have a weak battery.