Question

What is the fastest SQL Server connection protocol?

Related: which protocols are available remote versus local, and does that affect the choice of fastest protocol?

Answer 1

VIA. This is the fastest SQL Protocol, it runs on dedicated hardware and is used in doing SQL Server benchmarked records.

Note that the VIA protocol is deprecated
by Microsoft, and will be removed in a
future version of Microsoft SQL Server.
It is however supported in SQL Server 2008,
SQL Server 2008 R2 and SQL Server 2012.

Shared Memory is next as performance, but it only works between a client and a server that can actually share memory, so local only.

For remote connectivity on ordinary hardware, TCP is the way to go. Under normal operations, it has the same performance as Named Pipes. On slow or busy networks, it outperforms NP in robustness and speed, a fact documented in MSDN:

For named pipes, network
communications are typically more
interactive. A peer does not send data
until another peer asks for it using a
read command. A network read typically
involves a series of peek named pipes
messages before it starts to read the
data. These can be very costly in a
slow network and cause excessive
network traffic, which in turn affects
other network clients.

Named Pipes also can lead to client connect time outs:

TCP/IP Sockets also support a backlog
queue. This can provide a limited
smoothing effect compared to named
pipes that could lead to pipe-busy
errors when you are trying to connect
to SQL Server.

Unfortunately the normal client configuration tries NP first and this can cause connectivity problems (for the reasons cited above), where enforcing TCP on client network config (or in connection string, via tcp:servername) skips the NP connect attempt and goes straight to TCP for a much better experience under load.

Now is true that the same link I quoted above goes on to praise NP for its easy of configuration, most likely referring to no need to open SQL TCP port in firewall, but is there where me and BOL have different views.