Update website

Author: mbloch

mapshaper.js

@@ -17219,6 +17219,29 @@
     profileStart('snapAndCut');
     var arcs = dataset.arcs;
     var cutOpts = snapDist > 0 ? {tolerance: snapDist} : {tolerance: 0};
+
+    // Probe for intersections before any modification. If the input has none,
+    // every pass of the loop below is provably a no-op: snap() can only
+    // consolidate FP noise around intersection points, cutPathsAtIntersections
+    // inserts cut points only where segments cross, and buildTopology is gated
+    // on coordsHaveChanged. So we can return early and skip a ~O(V log V) snap
+    // that would snap zero points, which is the dominant cost of robust
+    // dissolve on already-clean polygon input.
+    //
+    // limit=1 makes the probe cheap on dirty input too — it stops the stripe
+    // scan after the first hit, so the probe's full cost is only paid on
+    // truly clean input (where it replaces the equivalent scan that
+    // cutPathsAtIntersections would otherwise do on pass 1).
+    var probeOpts = {tolerance: cutOpts.tolerance, limit: 1};
+    profileStart('probeIntersections');
+    var probe = findSegmentIntersections(arcs, probeOpts);
+    profileEnd('probeIntersections');
+    if (probe.length === 0) {
+      debug('[snapAndCut] skipped (no intersections)');
+      profileEnd('snapAndCut');
+      return false;
+    }
+
     var coordsHaveChanged = false;
     var snapCount = 0, dupeCount, cutCount;
     var maxLoops = 4, loopCount = 0;

sponsor.html

@@ -186,14 +186,14 @@
 
 <h1>Support mapshaper</h1>
 
-<p class="tagline">Mapshaper is free, open-source software for editing geographic data &mdash; used worldwide for everything from classroom exercises to professional map work.</p>
+<p class="tagline">Mapshaper is free, open-source software for editing geographic data &mdash; used worldwide for everything from student projects to professional map work.</p>
 
 <div class="sponsor-buttons">
-  <a href="https://ko-fi.com/mapshaper" class="btn">Support via Ko-fi</a>
   <a href="https://github.com/sponsors/mbloch" class="btn btn-secondary">Sponsor on GitHub</a>
+  <a href="https://ko-fi.com/mapshaper" class="btn">Tip the developer</a>
 </div>
 
-<p class="sponsor-note">Ko-fi accepts one-time or recurring contributions &mdash; no account required. GitHub Sponsors offers recurring sponsorship.</p>
+<!-- <p class="sponsor-note">Ko-fi accepts one-time or recurring contributions &mdash; no account required. GitHub Sponsors offers recurring sponsorship.</p> -->
 
 <h2>What your contribution supports</h2>
 <ul class="support-list">