I use the search/replace feature in Wikipedia (not the browser). The highlighted results are not synchronised with "find next" button. Hence, 95% of time I have to scroll up & down the whole text to find the highlighted result each time I click find next. Also, sometimes some results are not highlighted at all (last time this happened was today when I was searching for double spaces in an article).
This might be only my computer but I'm not sure how can I find out.