Windows 7 Gadgets slow to respond, 50% CPU utilisation with gadgets that "move"

Question

I have a fresh installation of Windows 7 RC and everything was fine. I have no idea what may have caused this, but on day 2 of using Windows 7 RC, any desktop gadgets that move (like the CPU meter or the clock with its second hand enabled) cause the sidebar.exe process to go to 50% CPU utilisation (which is 100% of one core on my dual core CPU).
These gadgets then just become unresponsive and I have to close them. I can only keep the Weather gadget on because it doesn't have any animations. I have all Windows updates and the latest NVIDIA driver from Windows Update and even their own website doesn't help. There is something wrong with my gadgets. I have never installed any extra gadgets.
What could it be?

Answer 1

Same issue, but after Vista x64 Home Prem upgrade to Win7 Home Prem x64.  ATI Radeon HD 4850 graphics card, Quad Core & can't even change the settings of the Clock if I set the seconds hand.  The clock takes up a continuous full core (25% of overall CPU) while the seconds hand is running; if the seconds hand is off then CPU utilization is 0% between minute updates.  Other gadgets are similar, but many such as Calendar, Weather, and some non-MS gadgets work perfectly fine.  Must be some kind of javascript issue.  I have Avira Antivir before & after upgrade to Win7, so AVG isn't the issue for me - I even tried with Antivir and Comodo Firewall turned off. UAC on. 
This machine is FAST & it can't handle a little gadget.  (7.2/7.3 Windows Experience subscores on all but hard disk, which is 5.9)  Didn't have this issue in Vista x64 Home Prem.
edit:
Checked the Win7 Resource Monitor CPU tab:
sidebar.exe - While not under heavy CPU load, "Analyze Wait Chain..." from context menu continually shows "One or more threads of sidebar.exe are waiting to finish network I/O", and indicates thread 4140 which is WinInet.dll (Internet Extensions for Win32 application extension.)  Under heavy CPU load, several other threads starting from sidebar.exe were indicated from the same message from "Analyze Wait Chain..." as well.
All other non-sidebar processes indicate "running normally" from "Analyze Wait Chain..."
Another clue:  If I login using the "Administrator" account, there is *** no performance problem ***!  The sidebar.exe shows as "running normally" from "Analyze Wait Chain..." 
So I also tried:
- w/UAC turned off on the normal user (administrator rights) account (no fix)
- tried creating a *new* normal user (administrator rights) account; still sloooowwww (also try this one w/o UAC, still bad)
-Problem Status:  normal User Accounts have the sidebar performance problem, Administrator account runs fine.
Edit: 12/31/09
SOLVED!!!!
After digging into the sidebar.exe output from Sysinternals Process Monitor, I noticed a peculiar difference between the output for the properly functioning Administrator account & my User accounts.  The admin acct showed the monitor profile for a good number of operations, while the User accts showed the wsRGB.cdmp value for the same operations, which was peculiar because I had my User accounts configured to use the system defaults, the same way I had the admin acct configured.
Going into the Windows Color Management, Advanced tab, I found that if I chose either of the "virtual device model profile" choices for the "Device Profile" setting, the performance hit was instant.  If I used any of the "normal" icm profiles, performance was good.  So I changed my system default Device Profile from "sRGB virtual device model profile" to the std sRGB.icm profile & everything is working great!
Note: In addition to the Gadgets, this also impacted the Windows Media Center Internet TV listings performance, which was also back to good performance after this WCM setting change.  I'd expect there are numerous other apps that could be affected by the "virtual device model profile" handling.  Googling "virtual device model profile" seems to bear that out, as I see others who ran into app problems when using that in the WCM applet.