Web3000 Inc has surpassed one million registered customer for its NetSonic internet accelerator tool, it will announce today. Available since April 1998, it is currently the fourth most popular software download across all software categories on CNet Inc’s Download.com site and has regularly topped the pile over the past few months. The Redmond, Washington-based company announced NetSonic Pro, the $40 version, in October last year. NetSonic works by locally caching copies of previously-visited pages and only updating things that have changed. Privately-held Web3000 closed its first round of VC funding in November, raising about $1m and has now opened round B.