When you say the system was slow, what do you mean specifically? I've got zstyle on my 3100 (Cacko 1.23 Lite, without Japanese software yet) and it seems to be working okay. The font modification seems to working normally as well.
As for the 3k, it seems that for the stock rom, setting it to an English locale and using zStyle to re-enable the Japanese fonts for input seems to work much better than using the Stubear's translation script.
More testing to be done.
So, i installed zstyle. Then I restarted. After the restart the tab navigation became slow. Also when i clicked on the icons, the system responded with a lag. The overall performance was terrible. I have cacko 1.23 full with japanese packages installed.
By the way, thanks a lot for testing and trying new things.