If "shared" attribute is "true" for files in an extension, Extension Manager has to do many checks when removing or updating this extension. It is time consuming. If the number of shared files is large, the time needed is extremely long ( might be more than 20 minutes ). Extension Manager CS6 did some optimization for this issue. But for Extension Manager CS5.5 or earlier, this issue still exists. We suggest extension developers do not use "shared" attribute for files if it is not necessary.