Many programs and services run immediately at boot on current Windows systems. This has long been known to cause some very heavy disk-thrashing while the machine is starting up. There is a new option available with Windows Vista that allows for a delayed startup. Services started with a delayed start type will still start up without user interaction, but they won't all try to start as soon as the user logs in.

The obvious benefit is that once a program is set up for a delayed start, Windows Vista can start it up when the system is quiet. That will have a big impact on the user perception of start up times. Generally, when a computer starts up with Windows today the user expects to wait for the hard drive to stop grinding before they attempt to do anything. Sometimes they've determined that there's a visual cue, such as the icons on the desktop blinking out then reappearing. Users feel that their computer is slow and unresponsive when they see this happen.

Slow startup times are worse than they sound because many users have a real expectation that they've turned on the computer to do a particular task. That task can be forgotten or distorted while they sit, glassy-eyed, waiting for the system to settle to a ready-to-run state. The delay they experience is a form of negative feedback for attempting to use a computer to accomplish their task. This negative feedback means the user is more likely to avoid the computer next time.

So overall it seems that a delayed start for tasks that don't need to run immediately is helpful. The side-effects that could arise can be less obvious however. When a service is started but fails or crashes, it often reports the error to the user in a popup message box. That popup message box would come up before any user action currently. Since the message box shows up before any user action it is apparent that it isn't caused by the user's actions. With a delayed start the message box could come up while the user is working and the user could perceive the message box to be a response to their actions. This can slow down troubleshooting the problem as the user investigates problems that aren't really there.

Good even logging when a delayed task starts should help clear up some of the issues that might arise. Although it doesn't look like it at first glance, this should be a significant improvement to the average user's experience with a Windows Vista PC.