On 04-09-12 10:50, Mark Crutch wrote:
... The real problem is the number of filtered pixels to be calculated. A box that's 100x100 pixels at one zoom level will be 50x50 or 500x500 at others. Because filters are (generally) bitmap operations that apply to each pixel in the filtered area (and beyond), more pixels means more calculations, means slower redraws. ...
Never underestimate the power of a modern computer :) A typical PC is able to fill your screen MANY, MANY times per second in terms of sheer computational power. The only problem is getting the code to actually run at full speed... In Inkscape's case we're doing more work than necessary, and we're probably also not arranging the work in the most efficient manner. And it is unfortunately non-trivial to do better (not impossible, but it's definitely not a quick fix kind of thing).
(You are absolutely right that with something like blur you often need to draw more than what is visible though.)