Fast deserialization/reserialization is critical for databases. The key is to deserialize only what you need and to keep the serialized data for items that have not been changed for reserialization after an update.
JID can deserialize/update/reserialize a map of 10,000 entries in 4 milliseconds, running on an i5 at 2.53 GHz, where deserialization/reserialization timings are largely independent of the size and complexity of the table entries. That's 400 nanoseconds per table entry.
JID is written in Java under LGPL and builds on the JActor project.