I notice that your Usercache is 0 as well. This looks interesting and maybe something that you can help set up for me once you let this run for a few days to see its effect.Interestingly I installed Igbinary and set PHP to use it as the session serializer, I then decided to use Igbinary as the serializer for APC expecting to see memory footprint reductions, but I didn't see that (well I believe I have got memory reductions looking at the graph but resident memory size of files hasn't changed according to apc.php. Speed wise it is very difficult to tell if there is speedup. One thing I did notice was that my fragmentation is now virtual non-existant as the following graphic shows (normally by this time it is fragmented to hell)
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My fragmentation hits 100% within 24 hours and in 2-3 days the cache full count starts to grown so if this help eliminate the needs to restart APC, it's a welcome thing.