Everytime that I run a PowerCore plug-in, it adds latency to the track. The latency only appears when I run a PowerCore plug-in; native RTAS plug-ins work perfectly. What is going on?
What you experience, is perfectly normal and a limitation of Pro Tools LE / M-Powered.
Pro Tools LE / M-Powered doesn't have latency compensation, for DSP-hosted plug-ins. Pro Tools HD does, but LE / M-Powered doesn't.
The only workaround, is to use the TC Compensator, which can help you set up a uniform latency, among all your tracks, so they're all delayed by the same amount and back in sync with each other.