From DBSight Full-Text Search Engine/Platform Wiki
This is directly from a customer with lots of visits for their website to search product catalog. All 7 indexes are loaded into memories. And you can see, it's pretty fast.
OS Name Linux OS Version 2.6.9-34.0.2.EL JVM Vendor Sun Microsystems Inc. JVM Version 1.5.0_08-b03 Total Memory 980.85 MB Free Memory 355.83 MB Max Memory 1016.12 MB