Speed up a slow computer or phone

Help me speed up a slow device.

Device: [phone / laptop — make]
Symptoms: [slow apps, heat, battery]
Storage status: [full / unknown]
Age roughly: [years]
What I've tried: [optional]

Ask me up to 3 short questions first if anything important is missing. Wait for my answers.

Then:
1. Safe checks (storage, updates, restart, background apps).
2. What to delete or offload first.
3. Settings worth checking on this platform in general terms.
4. When replacement is more realistic than repair — without a product push.

Only use what I've told you, leave blanks for anything I haven't given, and don't invent facts, steps or official URLs you're not sure of. UK English.

Stay in this ChatGPT chat. Do not turn on apps or connectors, and do not use memory from another chat.