MATLAB slowing my laptop down?

Okay so my Ideapad 330 laptop was running pretty normally, when I installed MATLAB. As I have read in other posts here, MATLAB can be slow and my ram is 4 GB with i5 processor - my peeps say that 8 GB with i5 would be better and make it smoother. MATLAB was running slowly yes, but not massively slow. Like it would take 2-3 mins to start and programs of 50-60 lines would take around 40 secs for execution - things were going normal for about a month. BUT recently, they are taking a long, long time!!! Like, seriously?!! And my laptop actually hangs! And all of the other open softwares (Adobe reader, Chrome, etc) get ridiculously slow too. The pointer/cursor even doesn't move! It responds after 5 mins! And forget about MATLAB. Even 30 lines' codes take forever to execute. The entire thing just freezes -works for 1 second - again freezes. And then I am forced to long press the power button and shut this annoying this up! If I don't open MATLAB, then the laptop works cool. But once....I open.....I am doomed for the day. I don't know.. is it cuz of MATLAB or...something else? It was okay for a month. But what happened to it suddenly?

Please help! My programming sessions are giving me nightmares!

In case it helps, I have not installed any other software after MATLAB. I have an older version of MATLAB in this laptop too. I tried deleting it but there were some errors...and R2018b was working fine, so I didn't bother much about deleting the older version. And all I do on my laptop is, browse the net, play songs and read pdfs for academics.