If you need to run Windows applications on your Mac, you have two options: Use Bootcamp to boot into a separate partition of Windows, or run a virtual copy of Windows using either Parallels Desktop 9 or VMWare Fusion 6.
What's New with Parallels 9
The biggest draw of Parallels 9 is the performance increase, which I will discuss in the next section. The Parallels Desktop 9 also takes advantage of OSX 10.9 Mavericks power nap feature, enabling updates to Windows VMs while asleep. In addition, Parallels has added support support for cloud services (e.g. iCloud, Dropbox, Google Drive, SkyDrive). DirectX 10 support has also been added, which seems to have cleaned up a lot of the glitchy window behavior that used to occur while in Coherence mode.
Parallels Desktop 9 for Mac Performance
I'm unfortunately bound to Outlook 2013, so I use Windows on a daily basis. The most immediate and noticeable update I noticed with Parallels 9 is the startup and shutdown time. Based on my own time (compared to my results last year), performance is up significantly. Startup and shutdown have been reduced by about 25%. I takes me exactly 12 seconds to fully boot into Windows 8 — that's pretty impressive.
Disk performance is also up, with Arstechnia reporting an average increase of about 40%.
Parallels 9 is Really Fast
Where I’ve noticed the speed improvement most of all is when on launching, sleeping and waking, and shutting down virtual machines. As mentioned before, the biggest difference is in disk performance, with a whopping 40% improvement.
The performance comparison chart below is available as part of a larger comparison on Arstechnia, but the difference is clear.
To be fair, MacWorld released a comparison of Parallels Desktop 9 and VMWare Fusion 6 which resulted in “neck and neck” performance. However, my own results differed greatly.
Integrated Windows 8.1 Start Menu
During the installation of Windows 8 (or 8.1), Parallels Desktop 9 allows you to choose your Windows Experience: like Windows 8 or like Windows 7. In Windows 7 mode, Windows boots directly to the Desktop, Modern UI apps run inside separate windows, and the Windows Start menu is back and fully-functional! This is accomplished using the awesome Start8 application by Stardock. Even though Windows 8.1 has the ability to use a start-like menu, Microsoft's implementation is complete shit. It's barely a start menu. Start8 has been the absolute best. Period.
There's not really much more I can say. I have been a Parallels fan for years, and if the quality of future performance and releases continues, I will be for years. You can download a free trial of Parallels Desktop 9 by clicking on that link.