Replaced LCD screen now super slow and fan runs fast.

No not hot at all, with the TG Pro app installed I can see the temp and it isn't running hot at all. I don't believe it was ever hot before either. I feel like I would have noticed it and I didn't have the fan issue until I replaced the new LCD. Yes, everything is super slow even internet connection loading pages. I work with Photoshop and Lightroom and they are painfully slow. {and I installed a 2TB SSD dive that was lighting fast before I replaced the LCD. :-( }

What brand of SSD did you install and how long ago? That might explain the slowness. The fan speed I am not sure what would cause that.

Crucial SSD drive and it was 7 months ago and was working great until i replaces the LCD screen

@jolenebroad were you able to resolve the loud fan and slow iMac after replacing the LCD? I just did the same to my Late 2012 27 iMac and I'm having the same issue!

I ended up taking it to a certified Mac guy and he opened it up and had to fix a part that plugs into the fan but mine had to do with the new front glass I broke so maybe not the same for you but there was a part of the fan that needed work.