This being a Chromebook, we couldn't run our usual suite of benchmarks for Windows. Instead, we used Futuremark's Peacekeeper browser benchmark. It achieved a score of 1,370, which (according to Futuremark's own benchmark database) is four times quicker than an Asus Eee Pad Transformer Prime, which scored 344, or Microsoft's original Surface, which managed 348. Even an Apple iPad 4th Gen only achieved 951.
However, in other third-party tests we have seen the Acer C720 achieve 2,828, more than twice that of the C300, so it isn't particularly fast as Chromebooks go. It does have another trick up its sleeve, though. Peacekeeper also has a battery test, which we tried on the C300. It lasted a whopping 9 hours and 21 minutes, with an average score of 1,371 – pretty much exactly the same as on the mains. So you can use the C300 for more than a working day, or most of a lengthy international flight. The 1.4kg weight and 20.3mm thickness further aid this portability.