If a translation fault is the same or similar to a page fault, which I suspect it is, then you are right in thinking that a cache hit rate that low is not typical. A large number of page faults is not a problem -- a page fault isn't an error, it just means that the virtual memory system needed a page of memory that wasn't already in physical RAM. It's bad only because it means you need to page memory in from disk, which takes awhile. The object cache, assuming it's the same thing I'm familiar with, is a list of page-frame mappings that allows the system to quickly reload a page that it recently paged out without referring to the page table (don't worry if that seems obscure -- it is). My current hit rate is something like 88%, but I've just been browsing the Web for the past half hour and not opening many different programs or (presumably) calling too many different functions. So the best answer I can give is that none of that is a problem in and of itself, although if your cache hit rate never goes above 50% even when you're just putzing around in Safari or something, that could be a signal that something's amiss -- try running top and take a look at your load averages and free memory; if something's hogging your processor in the background every couple minutes, it could theoretically cause the sort of low hit rate you're seeing (though I'd be surprised if that was the case). Above all though, the object cache is just an optimization mechanism in the virtual memory system, so if you haven't noticed your system slowing down or your hard drive churning, and especially if your pageins and pageouts in top aren't unnaturally high (you can check what "unnaturally high" means through another couple searches of the forum; just remember those numbers are cumulative, so if your computer's been up for three months they're likely to be big numbers), you're probably fine. If you're not noticing a slowdown, chances are everything's purring along just as it should be in general.
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