Hellow, Thank you for your work, Before, I used a local gadget for a long time in order to highlight the wiki syntax, That's perhaps why I know and I can say you did a really good job. This gadget doesn't slow down the browser and that's fine.
I only tried it during few hours, but I noticed the gadget interacts with the search feature of my broswer Firefox (32b, last version avail. + Win 7 64b). When I search for "blabla" in the wik ieditor text area (and the whole page), the search feature don't give all occurrences. If 10 or 20 "blabla" occurrences can be found, only 1 or 3 are found by the search feature. Disabling your gadget let the search engine works fine again.
I don't know if this bug comes from Firefox or the gadget. Perhaps it's a color problem ?
Regards