An efficient way to zest key limes? Due to my affinity for baked goods, I decided to try creating key lime pie filling from scratch. I've done so twice now using two recipes. The first of which calls for key lime zest as a primary ingredient. The second of which does not, though a recommended modification of the recipe, which I followed, does call for it.

Timing the process, it took me about 20-25 minutes to grate 3 tsp. of zest from my key limes using a planar grater/zester and a small ceramic bowl. I would like to significantly speed up this process if I can, but the size and texture of key limes makes them difficult to zest for more than a pinch at a time.

Is there a faster way? I was thinking of doing something crazy with my food processor or investing in a proper zester, though I'm not sure how much this would speed things along. There also seem to be rather expensive products like the Spin Zester out there, but they seem of dubious applicability to this problem.
It seems to me, that a quality planar grater is the best solution. The Spin Zester is way too expensive for a home kitchen. I can recommend this fine micro plane grater for zesting: