See attached project, DroolsBilling. You can build it with Maven from the project directory: mvn clean package To run it after building: java -jar target/DroolsBilling-1.0.jar <numRules> <numPhoneNumbersPerThread> $ java -server -jar target/DroolsBilling-1.0.jar 100 100000Rules load time: 3482msRules execution time: 732ms, per number: 0.00732msRules execution time: 731ms, per number: 0.00731msRules execution time: 746ms, per number: 0.00746msRules execution time: 760ms, per number: 0.0076msRules execution time: 832ms, per number: 0.00832msRules execution time: 623ms, per number: 0.00623msRules execution time: 600ms, per number: 0.0060msRules execution time: 632ms, per number: 0.00632msRules execution time: 630ms, per number: 0.0063msRules execution time: 607ms, per number: 0.00607msDONE! At higher numbers of rules you have to increase the perm gen and heap memory: $ java -server -Xmx1024M -XX:MaxPermSize=128M -jar target/DroolsBilling-1.0.jar 10000 100000Rules load time: 58317msRules execution time: 1580ms, per number: 0.0158msRules execution time: 1580ms, per number: 0.0158msRules execution time: 1586ms, per number: 0.01586msRules execution time: 2493ms, per number: 0.02493msRules execution time: 2502ms, per number: 0.02502msRules execution time: 1360ms, per number: 0.0136msRules execution time: 1358ms, per number: 0.01358msRules execution time: 1376ms, per number: 0.01376msRules execution time: 473ms, per number: 0.00473msRules execution time: 489ms, per number: 0.00489msDONE! As you can see the time to process one phone number is lower than 1 minute. :)  The example uses 5 concurrent threads and was executed on a 4 core machine. A Sample.drl is included that shows the format of the rules generated, basically this: rule "PhoneNumber000000000" when p : PhoneNumber( digit0 == '0', digit1 == '0', digit2 == '0', digit3 == '0', digit4 == '0', digit5 == '0', digit6 == '0', digit7 == '0', digit8 == '0', digit9 == '0') then p.setPrice(0.0);end They should be substantially similar to the rules generated behind the decision table you've given, so the performance should be similar.  As you can see from the times above, rule creation is expensive but execution is cheap.  As Mark said, reuse the KnowledgeBase. --- On Tue, 5/18/10, Antonio Anderson Souza <antonio(a)voicetechnology.com.br&gt; wrote: From: Antonio Anderson Souza <antonio(a)voicetechnology.com.br&gt; Subject: Re: [rules-users] Jbilling Drools performance To: "Rules Users List" <rules-users(a)lists.jboss.org&gt; Date: Tuesday, May 18, 2010, 4:11 PM Greg, CDR is a Call Detail Record, sorry I forgot to explain it, the object is a POJO with the following attributes: field: name: datereference type: DATE value: 2010-04-28 00:00:00.0 field: name: billingid type: STRING value: 20100428.15544.42adf field: name: accountid type: INTEGER value: 15544 field: name: billingperiod type: STRING value: 20100401 field: name: billingclassification type: STRING value: DUR field: name: ipxcallguid type: STRING value: 5k692927-guwtka-g8kj8d0u-1-g8krry54-o4n field: name: transactiondatetime type: DATE value: 2010-04-28 20:21:01.337 field: name: billingitemid type: INTEGER value: 0 field: name: ratesystem type: STRING value: IPXNET field: name: originnumber type: STRING value: 551135880520(a)bitcompany.braste field: name: destinationnumber type: STRING value: 551139012650 field: name: destinationareaid type: STRING value: 100000551 field: name: chargedduration type: DATE value: 1980-01-01 00:02:06.0 field: name: chargedamount type: FLOAT value: 0.0816 field: name: userid type: INTEGER value: 3372 field: name: username type: STRING value: bitcom51 field: name: unitamount type: FLOAT value: 0.00389 field: name: amountcurrency type: STRING value: USD field: name: timezone type: INTEGER value: -3 field: name: registertype type: STRING value: MV field: name: datelastupdated type: DATE value: 2010-04-29 02:57:18.54 field: name: lastupdatedby type: STRING value: IPXRateCalls rev032 field: name: lastupdateremarks type: STRING value: null field: name: dateinserted type: DATE value: 2010-04-29 02:57:18.54 field: name: destinationdetail type: STRING value: SAO PAULO field: name: type type: STRING value: Fixo field: name: collectedcallflag type: INTEGER value: 0 field: name: jb_timestamp type: DATE value: null field: name: digit0 type: INTEGER value: 5 field: name: digit1 type: INTEGER value: 5 field: name: digit2 type: INTEGER value: 1 field: name: digit3 type: INTEGER value: 1 field: name: digit4 type: INTEGER value: 3 field: name: digit5 type: INTEGER value: 9 field: name: digit6 type: INTEGER value: 0 field: name: digit7 type: INTEGER value: 1 field: name: digit8 type: INTEGER value: 2 field: name: digit9 type: INTEGER value: 6 field: name: digit10 type: INTEGER value: 5 field: name: digit11 type: INTEGER value: 0 This spreadsheet is only a sample because the whole one has 40000 rules, I'm checking the Jbilling code, but it seams to be loading the rules each time. Best regards, Antonio Anderson Souza Voice Technology http://www.antonioams.com 2010/5/18 Greg Barton <greg_barton(a)yahoo.com&gt; OK, so a few questions: What is a CDR?  How much data does it contain?  Do you load the rules fresh each time you process one?  Are there other rules besides the ones listed in the decision table?