Hazel and high MDS CPU usage

I find that on a fairly regular basis, Hazel hits 15-20% of my CPU, (Leopard, Macbook 1.83 C2D, 2Gb). What I've noticed is that when that happens, MDS hits 40% or more as well. I've noticed this on a daily basis over the last two months. This is, perhaps not coincidentally, also about the time I started using Fresh to tag files using Openmeta, and creating file-sorting rules with Hazel. Something comes into my download folder, I tag it, and Hazel shuffles it off into the appropriate sub-sub-sub folder. I know MDS has to do with Spotlight.

Any suggestions? Are my tag-based rules causing this?

I've actually started disabling Hazel except when I know I have something I want it to filter.

Thanks

Is there a reason why you are still using OpenMeta instead of native tagging? If you stop Hazel, do you get the same rise in MDS usage?