I don't know if it's useful (or even relevant) but I've loaded !TaskUsage to see what is happening in terms of processor use by NetSurf. Here's the results (RO 5.16, NS r10654): -
NetSurf loaded on iconbar, no window open: 0% NetSurf homepage fully loaded and displayed without having focus: 0% NetSurf homepage fully loaded and displayed with focus, without pointer: 0% NetSurf homepage fully loaded and displayed with focus, with pointer over window: 57-61% NetSurf on ROOL Forum list page <http://www.riscosopen.org/forum/>, scrolled top to bottom with scroll bar: peak 45% NetSurf on ROOL Forum list page, scrolled top to bottom with scroll wheel: 93-100% per scroll wheel movement. -- Grahame Parish