Ps4 pro keeps freezing, help.

I have a pro for a year, it started freezing a little and then it does it in every game even disk offline. I think I it happened after PlayStation update 7.51. I had error code which was just normal code straight after update. I have done everything in safe mode including reinstalling from usb, twice. Takes ages to down load games, especially the graphic side, textures. I am at a loss, do I but a new hard drive, will that work or am I wasting money. Any help would be great. I am going to take apart to clean in case it’s blocked or thermal paste is dry, but unsure if those issues would cause this as not getting a ps is hot  warning. Help please. Thank will. P.s can PlayStation get firmware virus.