In SQL, is UPDATE always faster than DELETE+INSERT?

Question

Say I have a simple table that has the following fields:

1. ID: int, autoincremental (identity), primary key
2. Name: varchar(50), unique, has unique index<

Answer 1

I am afraid the body of your question is unrelated to title question.

If to answer the title:

In SQL, is UPDATE always faster than DELETE+INSERT?

then answer is NO!

Just google for

• "Expensive direct update"* "sql server"
• "deferred update"* "sql server"

Such update(s) result in more costly (more processing) realization of update through insert+update than direct insert+update. These are the cases when

• one updates the field with unique (or primary) key or
• when the new data does not fit (is bigger) in the pre-update row space allocated (or even maximum row size),resulting in fragmentation,
• etc.

My fast (non-exhaustive) search, not pretending to be covering one, gave me [1], [2]

[1]
Update Operations
(Sybase® SQL Server Performance and Tuning Guide
Chapter 7: The SQL Server Query Optimizer)
http://www.lcard.ru/~nail/sybase/perf/11500.htm
[2]
UPDATE Statements May be Replicated as DELETE/INSERT Pairs
http://support.microsoft.com/kb/238254