[rules-users] Poor performance from a simple join

Folks: My co-workers and I have been using Drools to great success, but we ran smack into a performance brick wall recently. In the example below, both BINNING_INPUT and LU_DEVICE_TYPE have large numbers of associated facts in working memory (BINNING_INPUT has more than 8 million facts in working memory, LU_DEVICE_TYPE about 10k.) LU_DEVICE_TYPE models a lookup table. rule "Binning for Attribute: Device_type_desc" when $call : BINNING_INPUT() $device_typeLookup : LU_DEVICE_TYPE( $call.device_type == device_type ) then $call.setDevice_type_desc($device_typeLookup.getDevice_type_desc()); end It's a simple enough rule: join on the device_type field. Unfortunately, this rule and a few others like it are taking FOREVER to insert. Even when I cut the number of BINNING_INPUT facts in working memory down from 8M to 10k. This feels like a basic Drools question. But I can't seem to find any help from google. Please advise! Thanks in advance, Dave Martin