If you have complex geometry - particularly surfaces with compound curvature or large numbers of holes - you can get better dragging performance by turning OFF the 8th button on the text window toolbar "Hide Edges of Solid Model".

This does not affect zooming or rotating, but when dragging something that changes the geometry it can drastically increase your frame rate.

For the curious. Those edges are drawn by OpenGL, but some view-independent analysis of the triangle mesh has to be done first and this is a slow algorithm that does not take advantage of multi-core processors. The analysis only has to be redone if the triangle mesh changes, which is why rotation, panning, and zooming remain fast even when showing the edges.