(Redirected) OptiPlex 7010 ultra slow SSD operation

Introduction:

1. On OptiPlex 7010 with Win 8.1,  I am switching from 1TB HDD to 500 GB Samsung EVO 850.
2. All drivers are updated, BIOS refreshed to the newest. To transfer data I am using Samsung Data Migration.
3. Fully updated system works OK with original 1TB HDD

Result of migration:

1. System boot slow
2. System operation extremely slow.

Base on Internet reading I have the following Questions:

1. Is slow op a result of bad SSD?
2. Is slow op a result of Dell dislike of Samsung SSD ;-)
3. Does anyone knows Anything unusual about OptiPlex 7010 (Marvel chip, capacitors, or any other hidden gems)? (Software is updated so I am assuming it is a configuration setup or HW)

Appreciate a response