Update 2010: This project went nowhere.
Sun is about to release Project Looking Glass, a 3D user interface that that is a cross between Windows and a poorly written game. The step from Windows to the 3D desktop is equivalent to the step from Windows 2000 to Windows XP multiplied by 10. If you are one of the millions who immediately click the "turn off everything XP" option in XP then you will hate the 3D desktop even more than XP.
Update 2010: This project wasted screen space and everyone wants more screen space for their applications, not the operating system. Handheld devices are the big fashion. Horizontal sliding is used everyhwere but not the Sun style rotating. Microsoft's Vista was an equivalent disaster. We want speed, not decoration.
Even the screenshot demo is slow and that does not make you wait through the whole painful process. We can work out the potential slowdown by comparing the downgrade from Windows 2000 to XP.
When you stop from Windows 2000 to XP on a normal medium priced computer, similar to my workstation, 0.5 second actions slow down to 1.0 second. On a medium level Dell, the same action drops from 1 second to as long as 12 seconds. A quick click on the XP "work like Windows 2000" button brings XP back to almost Windows 2000 speed.
Experiments with a wide range of 3D user interfaces show the 3D interfaces take from 3 times as long up to 20 times as long as 2D interfaces. Add the fact that no matter how fast you make the computer, the 3D interface has to slow down the screen updates to make the 3D action look 3D. If the extra graphics in XP slow a 1 second action down to 12 seconds, the Sun 3D interface will slow down the same action to somewhere between 36 seconds and 4 minutes.
You could suggest that modern 3D video cards would speed up the process. Yes, at up to $800 per computer for the upgrade. You also need more memory for the extra graphics. You need faster pipelines from memory to the processor to the graphics card, which means a motherboard upgrade. It is cheaper just to throw out your current computer and spend $2000 to $3000 on a new performance computer.
Dual Memory Channels
If your current computer has anything less than dual memory channels, you need a new motherboard, which brings you back to dumping your current computer. I recently upgraded a computer to dual memory channels and found a 50% speed increase. Straight after the memory upgrade, I updated some software. The software updates chewed up the speed increase.
You will need all the new features of the latest generation of computers just to keep up with application software updates. You are unlikely to have the spare capacity to run a 3D desktop.
Windows versus Linux versus Your Favourite Operating System
When you talk about desktop speed, lots of people jump in with stories about how their favourite operating system is faster. There are some differences in speed because of differences in code. If you installed Internet Explorer in NT, file accesses would slow down and the system would repeatedly crash because the clean 32 bit NT code would be redirected through the sloppy code in Internet Explorer.
Most of the speed differences are related to the overheads added to the operating system by the options you choose to add to the operating system. If you add file level security, file accesses slow down. If you add file journaling, file accesses slow down. The same happens when you add an extra graphics workload. XP is slower than Windows 2000 because XP has 3D style decorative bits. If you turn off the decoration, XP speeds up.
Some speed depends on hardware. Disks used to run at 5200 rpm. Now the common speed is 7200 rpm. If you update software while staying at 5200 rpm, you will notice an overall slowdown because your updated software will have larger files that take longer to load. Your best friend might make the same software update while switching to a new disk that happens to run at 7200 rpm. He or she might see an overall speed increase because the disk speeds up file accesses by more than the growth in file size. You see a slowdown and try to argue the case with someone who sees only a speed increase.
A lot of the 3D processing is unloaded to your video graphics processor (GP). If you switch to 3D while staying with the same computer, you will see a slowdown. If you buy a brand new computer with a much faster central processing unit (CPU), but only the same speed GP, you will see some applications speed up but an overall slowdown when you are in the user interface. If you buy a brand new computer with CPU that is only slightly faster but GP is a big step up, you will see everything jump up in speed.
Unexplainable delays can be the result of problems specific to your GP, specific to the chipset that connects your CPU to everything else, or to do with the way you install software. Some software simply wanders off to the Internet to look for stuff that it should store on your local computer. If you install a software update several times, you can mess up your disk with duplicated and fragmented files.
Think about the old Java multiple release problem. Two years ago Java applications used to be so sensitive that most applications arrived with their own release of Java. If you installed five Java based applications, you had five copies of Java installed. If you started those five applications, you had five complete copies of Java in memory. Today you usually need only one version of Java and usually have twice as much memory to hold multiple copies if you still happen to have multiple versions installed. The software problem is fixed and hardware is powerful enough to cope with the problem where the problem still exists.
Today's most common hidden delay seem to be virus scanners repeatedly scanning clean files. If you want a quick speed up in a corporate environment, install effective virus scanning in your network and remove the virus scanning from individual computers.
Do you remember the first uses of transparency and 3D? This was many years before Sun discovered either idea. In fact both were very old concepts way back in 1994 when they were used on a computer in the movie Disclosure.
The problem with transparency is the slow visual recognition of the displayed components. You save a lot of reading time and brain time if the computer simply displays the information side by side. You want the computer to do the work, not you. To save your brain power for useful things, avoid any interface that uses transparency.
The problem with 3D is that 3D only looks 3D if you introduce movement and deliberately keep the movement slow. Non moving 3D looks like the base relief 2.5D of XP. If your 3D rotates at a useful speed, each screen transition looks like a 2D screen flip rather than 3D. People stuck with 3D user interfaces in the early 1990s quickly switched off the 3D effects so they could get on with using the computer. Most people use 2D because 3D just does not work as fast as the human brain.
The Typewriter Analogy
Typewriter keyboards have stupid key layouts. One story is that the keys were deliberately jumbled up to slow down typists so the typists would not jamb the keys. The typists fingers worked faster than the mechanical keyboard. When the keys were mixed up, the typists had to think harder about each keystroke which then made their typing as slow as the hardware.
The 3D user interface makes the user interface slower than the human brain. To make the 3D user interface look useful, some suppliers will add lots of colour and perhaps moving pictures to distract our brains from the slow user interface. If you add enough movement and colour changes, our brains will be occupied with the recognition of the background information instead of recognising the information we really want. That will slow our brain down to the speed of the user interface.
The New Disease
After an hour of use, you will get a headache. Headaches are the most common symptom of poor user interface design. You get the same type of headache you would get if you were forced to read a notebook computer in very bright sunlight. 3D user interfaces give people the equivalent of RSI of the brain.
Desktop user interfaces are already too slow. The Sun 3D desktop makes things even slower. You will need massive hardware upgrades to make the 3D desktop approach usable. Your business will slow down if you use the 3D desktop. If you really want to improve the usefulness of your computer's user interface, choose NT, Windows 98, or one of the many 2D user interfaces available on Linux.