Like you, I am returning to the sport after a 4 year break, lastly in Nitro. Last time I ran or bought batteries was ten years ago on NiCad's. The biggest leap has to be with LiPo so you should already see an improvement with your motor using a Lipo. Although need to ensure your ESC can handle it. But hey, I'm only a beginner myself hunting down new ESCs and motors myself.
I have gained so much knowledge from people on here that I am sure far more experieced and knowledgeable people will soon be offering their expertise (of which I can learn from even more
Welcome back to the hobby and hope you enjoy it