Performance tip: On low-RAM, go to Developer Options → enable Don’t keep activities and set Background process limit to 2.
Why: Your /system partition is too small for the GApps variant you chose.
Fix: Use pico variant. Alternatively, use a GApps config file to remove unused languages (e.g., remove TTS and Hindi language packs). gapps android 6.0.1
Not all GApps are created equal. For Marshmallow, your choices are limited because most developers have moved on to Android 10+. However, the legacy builds are still rock-solid. Performance tip: On low-RAM, go to Developer Options