Cache improvements

At the moment we have huge numbers in the ehcache configuration, like 5000, 1000 elements in memory. Let's do some investigation/experiments and figure out the startup time and used RAM is different when we change those numbers.
Since we anyway don't know real statistics for the cache and thus can't configure it properly, I'd opt for decreasing the amount of elements in the cache if it decreases the demand for RAM and startup time.