Migrating to new iMac has slowed down the computer a lot

I just migrated from my 2009 MacBook Pro to a brand new iMac. One of the main reasons why I got the new computer is because the laptop was really slowing down. Now that I've migrated to the new iMac, essentially re-creating the laptop on the dekstop, it seems as though the speed didn't get any better. DId I migrate wrong? Should I not have migrated and just copied over each thing by itself? Any help would be appreciated.