Best way to merge adjacent polygons

[divil5000]

Hi, we are currently doing an offset (buffer) operation by a very small amount in order to take a whole load of polygons, some of which are abutting each other, and return a simplified list of fewer polygons, with the abutting ones merged into a whole.

It occurs to me that this is quite computationally inefficient though, and perhaps there's a better way to do it? We're currently using Clipper1 but planning our upgrade to Clipper2, so answers that apply in both versions would be wonderful.

Thanks!