Replace the naive per-char impl with scan-to

src/main/java/org/nsvformat/Nsv.java

@@ -11,17 +11,15 @@ public static List<List<String>> decode(String s) {
         List<String> row = new ArrayList<>();
         int start = 0;
 
-        for (int pos = 0; pos < s.length(); pos++) {
-            char c = s.charAt(pos);
-            if (c == '\n') {
-                if (pos - start >= 1) {
-                    row.add(unescape(s.substring(start, pos)));
-                } else {
-                    data.add(row);
-                    row = new ArrayList<>();
-                }
-                start = pos + 1;
+        int pos;
+        while ((pos = s.indexOf('\n', start)) >= 0) {
+            if (pos > start) {
+                row.add(unescape(s.substring(start, pos)));
+            } else {
+                data.add(row);
+                row = new ArrayList<>();
             }
+            start = pos + 1;
         }
 
         if (start < s.length()) {

src/main/java/org/nsvformat/Reader.java

@@ -13,25 +13,35 @@ public class Reader implements Iterator<List<String>> {
     private final List<String> rowBuffer = new ArrayList<>();
     private List<String> cachedRow = null;
 
+    private char[] buf = new char[8192];
+    private int bufPos = 0;
+    private int bufLen = 0;
+
     public Reader(java.io.Reader reader) {
         this.reader = reader;
     }
 
     private String tryReadLine() throws IOException {
         while (true) {
-            int c = reader.read();
-            if (c == -1) {
+            for (int i = bufPos; i < bufLen; i++) {
+                if (buf[i] == '\n') {
+                    // Line complete, return
+                    lineBuffer.append(buf, bufPos, i - bufPos);
+                    bufPos = i + 1;
+                    String line = lineBuffer.toString();
+                    lineBuffer.setLength(0);
+                    return line;
+                }
+            }
+            // Keep reading
+            lineBuffer.append(buf, bufPos, bufLen - bufPos);
+            bufLen = reader.read(buf, 0, buf.length);
+            bufPos = 0;
+            if (bufLen == -1) {
                 // Incomplete line at EOF, preserve lineBuffer for next call
+                bufLen = 0;
                 return null;
             }
-            if (c == '\n') {
-                // Line complete, return
-                String line = lineBuffer.toString();
-                lineBuffer.setLength(0);
-                return line;
-            }
-            // Keep reading
-            lineBuffer.append((char) c);
         }
     }