Is it considered a best practice or an overall performance boost for MySQL if I add an index to my table before
Even if the answer is obvious: Adding an index to a table before
SELECT ... WHERE statements and dropping them before
INSERT statements is really bad practice. And I'm pretty sure this holds true for every database.
You would have the overhead of creating an index entry for every row of the table on each
SELECT. That's far more costly than creating/updating an index entry once when a new row is inserted or updated.