Sub second.If I scan with an ES400, when the viewfinder clears the screen, you can just barely catch the data changing on the underlying screen.  Attached is a MyMobiler video attempting to show the response time. The viewfinder doesn't show on the video, so I had to key enter a few items to give you the idea.

I was wondering the same thing, and all of the web sites say that it's theoretically unlimited, so I built a simple item database with one table, 3 fields, but with 646k records.  It is 28meg and is indexed on the UPC field.  It works in neon.  I can scan an item and it comes up pretty quickly.  Not sure how long it would take to actually build the database on the device.  I cheated and used the tools from sqlite.org to build the database (imported from an old csv file) on the PC and copied it over to the device. You have to name it properly and add an entry in databases.db for it, but it works.

Dan,  When you make a lookup on an item and say that it comes up 'pretty quickly' can you quantify how long it takes typically in term of seconds? Best Regards, Ian Hatton