dell laptop improving speed E5430

got a refurbished Dell E5430. 

Recently its getting a little slower takes a while to boot and freezes when adding pictures to facebook. 

I think its 12 GB ram so shouldnt have an issues. 

Any hints and tips on improving performance? Speed? boot time? 

Or is it getting time to buy a new laptop with more RAM. Can I upgrade RAM on here or do anything please?

I am not good at speeding up laptops, normally buy a new one.