NI had this to say about warm up reads:
"It seems that the way shared variables works has changed from version 8.5 to 8.6. In 8.5, the variable connection is not set up until the first node is executed. This is why a "warm up" read is necessary in 8.5. In 8.6 however, the connection is set up as soon as the VI is executed. However this connection can still take some time, so in 8.6 all that really matters is that there is a large enough delay between when the VI is run, and when the shared variables are used. Therefore either method of the warm-up read or initial delay should give the VI enough time to create a connection."
Undeploying before deploying libraries:
"For the ... issue of restarting the [OPC] service with the variables deployed, ... this was similar to losing an internet connection and not being able to reconnect until you get an IP address. Apparently it is just simply faster to undeploy and redeploy than it is to wait for the deployed library to reconnect."
