[mcclim-devel] incremental redisplay optimization(?)

Hi,

The new(ish) code for optimizing incremental redisplay by replaying move-overlapping and erase-overlapping records all at once is actually a huge pessimization for many disconnected records: I think that region-union is a precise operation, so the asymptotic complexity of the union operation is O(n^2), and I think the complexity of the replay is O(n^3). Specifically, for my tablature editor, an operation which causes most records to be redraw takes 200 seconds with the current code, with most time (about 77%) being spent in BANDS-OP.

The attached fixes the performance problem by being a little less precise. Is it right?

Cheers,

Christophe