Can you do a test where much lower hit ratio?
Here it is with 100MB for a ~10GB working data set:
total=84.22 MB, free=15.78 MB, max=100 MB, blocks=1288, accesses=5078238, hits=3186246, hitRatio=62.74%, cachingAccesses=5078238, cachingHits=3186246, cachingHitsRatio=62.74%, evictions=11196, evicted=1890704, evictedPerRun=168.8731689453125
LRU Stats: total=84.09 MB, free=15.91 MB, max=100 MB, blocks=1286, accesses=6967721, hits=3189074, hitRatio=45.76%, cachingAccesses=6967721, cachingHits=3189074, cachingHitsRatio=45.76%, evictions=10876, evicted=1887926, evictedPerRun=173.58642578125
Again the hit ratio is much worse but in reality the hits were about the same in both cases. Included is the "time" output for those runs, the user cpu is somewhat higher (expected) but the total run time is really the same.