We're currently using JBoss Drools 4.0.3. We have a set of rules that is serialized to a file of about 10MB (about 2500 rules). When deserializing it, the addPackage() call takes about 2.5 minutes! Our code looks as follows: InputStream is = Test.class.getResourceAsStream("/Test.rules.binary"); ObjectInputStream ois = new ObjectInputStream(is); Package pkg = new Package(); pkg.readExternal(ois); RuleBase ruleBase = RuleBaseFactory.newRuleBase(); ruleBase.addPackage(pkg); // this takes 2.5 minutes ! Is this normal? Also, is there some documentation describing the expected performance of JBoss rules compilation and (de)serialization (and perhaps some tips on how to improve the performance)? Best regards, Davy Toch