I recently upgraded HDD to SSD on my mid-2012 macbook pro. After the SSD upgrade, the startup chime is delayed, causing slow booting of my mac.
Any potential pointers ?
The problem with cloning is that you are making an exact copy of all the data on your drive at the block level - including the deleted data.
Spinning media acts and breathes differently than solid state media (i.e. TRIM support) and as such, you will be introducing problems for your SSD where none existed on the HDD.
What do do instead?
Do a clean install and utilize Migration Assistant to transfer your user data.