The Windows 7 developers blog about some of the improvements in Windows 7 that should make the new operating system boot faster. The developers say 35% of Windows Vista SP1 systems boot in 30 seconds or less and 75% of the systems boot in 50 seconds or less. For Windows 7 they are shooting for a boot time of 15 seconds or less.
This sounds promising but we've heard this before a couple of years ago when Microsoft touted the improved boot time of Vista but that didn't turn out to be that spectacular at all.
One of the things the Windows 7 developers are working hard on is the system services, they aim to dramatically reduce them in number, as well as cut their CPU, disk and memory usage. They are also focused on increased parallelism of driver initialization, improvements in the prefetching logic and machanisms and improved tools to help users fix boot issues that can delay the bootup by many seconds.
As noted above, device and driver initialization can be a significant contributor as well. In Windows 7, we’ve focused very hard on increasing parallelism of driver initialization. This increased parallelism decreases the likelihood that a few slower devices/drivers will impact the overall boot time.
In terms of reading files from the disk, Windows 7 has improvements in the “prefetching” logic and mechanisms. Prefetching was introduced way back in Windows XP. Since today’s disks have differing performance characteristics, the scheduling logic has undergone some changes to keep pace and stay efficient. As an example, we are evaluating the prefetcher on today’s solid state storage devices, going so far as to question if is required at all. Ultimately, analysis and performance metrics captured on an individual system will dynamically determine the extent to which we utilize the prefetcher.
There are improved diagnostic experiences in Windows 7 as well. We aim to quickly identify specific issues on individual systems, and provide help to assist in resolving the issues. We believe this is an appropriate way to inform users about some problems, such as having too many startup applications or the presence of lengthy domain-oriented logon scripts. As many users know, having too many startup applications is often the cause of long boot times. Few users, however, are familiar with implications of having problematic boot or logon scripts. In Windows XP, Vista and in Windows 7, the default behavior for Windows is to log the user into the desktop without waiting for potentially lengthy networking initialization or scripts to run. In corporate environments, however, it is possible for IT organizations to change the default and configure client systems to contact servers across the network. Unfortunately, when configuring clients to run scripts, domain administrators typically do so in a synchronous and blocking fashion. As a result, boot and logon can take minutes if networking timeouts or server authentication issues exist. Additionally, those scripts can run very expensive programs that consume CPU, disk and memory resources.