Why does a parameterized query produces vastly slower query plan vs non-parameterized query?

It appears that the query planner has made a decision in the literal query which is based upon information that it already has. It would have statistics which it can query efficiently based on the spread of data given in your specific literal.

Your starting point should be the SQL profiler. Run both through the profiler, and see what the query plan is in each case... then update the question to describe the two plans.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.