Long terms issue - LR crashes on opening, after about 3 to 4 minutes picks up and runs normally

I have lived with this problem for ages (years) but am now getting mightily fed up!  The dreaded spinning wheel appears about 30 seconds after opening LR Classic and hangs there for about 5 minutes when it then stops and LR operates normally.  I have tried various suggestions such as turning off the GPU, updating my preferences, even loading a new copy of LR.  I thought updating my computer would work but the problem persists, through numerous sofware updates.  I also run LR on a laptop and have no issues with that version. Its almost as if there isa bug with my CC.  Any ideas?