iMac 12,2 - Likely hardware problem: How to properly diagnose?
Although your times seem too long, this could be due to your HDD. You said it was replaced, any idea on the specs?  A slow drive can be indicated by the problem you describe. Loading an app may be very slow since it is being read off the HDD. Once loaded the speed will be determined by your RAM unless you output a lot of data to disk.