third party plugins ... very slow

i'm looking for a nice Glitch/Distortion/Dirt FX
so i downloaded trials of mGlitch and Damage
they both do what i'm looking for but both render very slow compared to the FX that come with FCPX - they use only 20% of the CPU (i'm on a Dual Xeon MacPro)
especially mGlitch makes FCPX very slow to use.

Do you encounter this to and is there anything i could do to improve that. Would a newer GFX-card help (i have an nvidia 8800GT)

Have noticed that too, but not on all of them. Some of the very complex ones are very slow and a few just won't work on my machine. A quad core, Mac pro with 16GM of memory. Tried that Season's Greeting Card from the Mac Studio guys and it crashes FCPX every time and that is a rare event now that I am on 10.0.6. Have not had problem with the simpler one's even if they aren't using all the processing power. Saying goes you can't look a gift horse in the mouth and for the most part these freebees are very nice
and I respect those who are willing to contribute.

mGlitch is a very good set of templates from Motion VFX. All of their products are first class, but many of them are huge gobblers of system resources. I am using a 12 core MP with ATI HD 5870 Radeon card and for the most part they render fairly well with "High Quality" playback, but still need the horsepower.

You can try setting your preferences for "Better Playback" and you'll likely get better response. Not familiar with the nVidia card you have but 1G of video ram minimum will be good, 2G better.


ADDITIONAL INFO: Lucas Visual FX has a pretty good set of Grunge effects and transitions that might work for you. They won't be as CPU/GPU demanding as the mGlitch package. They are part of the Noise Industries FX Factory. Worth checking out.