late 2009 imac hanging after High Sierra upgrade from Sierra

I upgraded my Late 2009 27" IMAC I7 proccessor, 16GB Ram, 1TB HDD from Sierra to High Sierra. The upgrade went without issue and I was able to work with no issues. The IMAC stayed on all night and when I sat down to work the woke it up, signed in and it started hanging. I had to turn off the power and let it reboot. It must have taken 30 minutes to come back up and it is EXTREMELY slow and it will again hang where it seems now I will have to reboot it again.