The ListPicker control in Silverlight for Windows Phone Toolkit (Feb 2011 release) has become famous after its poor performance. My app IP CAM Controller for example, starts from v1.6, I used ListPicker to accommodate the full list of supported camera types and brands. The total item number is about 20 to 30, while it took 3 to 5 seconds to get response when openning the setup page. It's really a huge lag.
Thanks to Pedro Lamas who solved this problem by changing the source code in a few places. Details please refer to here:
It's not in english, but translator is available on the right up side of the page. He also submitted a patch to the official Toolkit project on CodePlex here:
patch ID 9632, providing a brief summary in english.
Good news for those lazy people (such as me), I attached the compiled binary and source file base on Pedro's blog, feel free to download from here.
Unzip the file and copy the two files (Microsoft.Phone.Controls.Toolkit.dll and Microsoft.Phone.Controls.Toolkit.pdb) to your Toolkit installation folder, e.g.
C:\Program Files\Microsoft SDKs\Windows Phone\v7.0\Toolkit\Feb11\Bin\