MacMini extremely slow, pinwheel at every entry... advice?

My MacMiini is exceedingly slow on a FiOS high speed connection. Pinwheel at every new screen and often typing delays with letters appearing several seconds after typed. I stay away from games and 3d party content (except Verizon messaging and an iTunes educational game for my granddaughter). I also use Chrome as my preferred browser. Any suggestions as to how to approach the problem?