My Minecraft lags and my laptop overheats

You may want to try updating your laptop.

Run Minecraft and open up the Task Manger, check what applications and processes are using your ram and cpu.

You may need to Uninstall or stop some apps from running.

Another alternative is to higher prioritize Minecraft, to do so...

When Minecraft is running, open up Taskmanager, go to details, right click 'Java.exe' or might be 'Minecraft' but not 'Minecraft launcher', click priority, then click above or high. This will adjust the priority of cpu is dedicated to that process compared to other applications.

Goodluck :)

Another couple of things you could do is

Check your laptop fan, Is it running? How much Dust is in their?

Do I open my laptop to check it? Opening your laptop to remove dust is a great Idea. Using the IFixit Tool set will help a lot. Ensure the battery and any chargers are removed from the Device before doing so. And touch something metal with your tools to remove any static electricity they may have, Otherwise you may fry some components. You can get an awesome work mat on the IFixit store I believe, It's a non-static one and it looks super handy. Make sure you take a couple pictures or atleast a drawing when you open the computer if you're going to remove any parts, Just in case you forget where something goes. ;) Last but not least, Just remember that opening a device usually ends a current warranty.

Hope this helps!