Some plug inslow down drastically my mac book pro

Hi , I'm wondering why some plugins are slowing down my sistem a lot , for istance if I use a Noise reductor ( Neat Video ) on a single clip final cut slow down and don't responde that much ( even skimming the clip is slow ) ...if I deactivate the plug in everything turn back to normality and fast use .

I m using FCP 10.1.3 on a middle 2011 MBP , SSD disk , OSX 10.9.5 , 8gb ram , 2gh core i7 ( hope this help )

Is denoise plug in that heavy for the system ?

Thanks

Yes, some plugins are resource hogs and can slow down your system.