[mcclim-devel] incremental redisplay optimization(?)

[Christophe Rhodes]

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?

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Cheers,

Christophe