[Utils] Cache performance issues - optimize reads operation

[gheorghitamutu]

While working on #181 & #182 several performance issues were encountered with the Cache module. After the initial read from file (by a size of max cache size) the subsequently reads are being performed with the requested size. This is an issue when a user calls the cache function for very small objects (2-400 bytes). We should cache a decent size on a read in order to avoid this - around 4-8k bytes.