I'm not convinced this is right actually Charles; caching does not significantly slow down rendering performance and needs defending. When I turn caching off in Xara 4, it is comparably fast to render the document at different zooms compared to the first render in which caching is also done. I thought the cache throttle ensured this was the case--limiting 5% of redraw time to caching. In other words, I don't see why caching makes it slower by more than 5% at max. (which usually equates to a small amount of time). (Even disabling cache throttling, thereby removing the 5% limit, negligibly impacts redraw times.) And once cached, it is much faster to zoom. Xara 2.0 shows identical findings. Xara 1--which didn't have any caching--performs similarly to the later versions with caching turned off.
In summary, I can't see the original problem here. However, the size of zoom step has also decreased for smoother zooming since 3.2, and again in 4, which may be being mistaken as the issue here.
EDIT: I understand the original description now. It was claimed that when zooming, before a new zoom level is drawn, the entire current view must be completely drawn, and that the older versions of Xara didn't require a full redraw before moving to the next zoom when scroll-wheeling. This is not true, and in all versions of Xara, the entire screen is required to be redrawn before the next zoom operation begins. I think the increased number of zoom steps has given the illusion that it is somehow 'not skipping' zoom steps. There isn't really a bug here, and essentially an effective call for larger zoom steps when wheel-zooming is being made I suspect.
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