Are you using Foreground search option or defaulting to background searches and are you searching in <Workspace> or <Project>? I suspect that you have wildcards defined in the project, and it's trying to match all the files that match the wildcard spec in the project in fairly deep or lengthy directory structure, and then has to match with the wildcard spec based on your search parameters. We have made some improvements to parsing project files in the 12.0.1 release, but even with that, wildcard specs still currently has some performance drawbacks.