with the release of Nuendo 4 and cubase 4.1, plugins that are 32bit will run slower because of translation. here is a quote from steinbergs knowledge base on their bitbridge.
You can imagine the VST Bridge as a kind of simultaneous translator for program code. There are no additional latencies introduced but the computer needs resources for the translation. A plug-in which runs through the VST Bridge can not be executed as efficiently a version available in native program code. Consequently, the usage of \"bridged\" plug-ins can result in higher CPU load and the plug-in user interface may react slowly