They conclude the new Opera browser is much faster than its competitors:
Opera claims that the latest version is faster than ever before, and our experience bears this out. When running various JavaScript speed tests, Opera 9.5 scored slightly higher (281ms) than the previous released version, 9.23 (546ms). And Opera 9.x, let it be known, smacks silly the likes of Firefox and Internet Explorer, which tend to have results in the 900-1500ms range on this test machine (a 1.8 GHz Core 2 Duo with 2GB RAM). Opera was 50 percent faster on average than Firefox, and 100 percent faster than IE7 on Windows Vista, for instance. (In all versions, the speed of the test depends on how many tabs are open, so your results may vary. In our experience, Opera always came out on top.)Source: ARS Technica
Opera also claims that the user interface itself also received significant optimizations for speed, and while it's tough to accurately benchmark this, the new alpha does feel slightly "snappier" than its predecessor.