> under-powered hardware ... one would think that for limited-scope usage (e.g. browsing ...), it should perform well.

Alas, I fear that browsing is probably one of the things that require good performance and a huge amount of software and complexity. Because browsing probably involves "checking Gmail" (huge amount of JS, need a good fast JS engine e.g. with JIT etc.) or "watching a YouTube video" (need to have video codecs correctly connected to the graphics card hardware), etc.