prevents I/O from dominating computation time when using progress

progress/__init__.py

@@ -66,18 +66,20 @@ class Infinite(object):
         pass
 
     def next(self, n=1):
-        if n > 0:
-            now = time()
-            dt = now - self._ts
-            if dt < self.time_threshold:
-                self._pending += n
-            else:
-                self._xput.append((n + self._pending) / dt)
-                self._ts = now
-                self._pending = 0
-
+        if n <= 0:
+            return
+        now = time()
+        dt = now - self._ts
+        if dt < self.time_threshold:
+            self._pending += n
+        else:
+            #   avoid performing computationally intensive update task
+            #       more than 1/dt (10 by default) times a second
+            self._xput.append((self._pending + n) / dt)
+            self._ts = now
+            self._pending = 0
+            self.update()
         self.index = self.index + n
-        self.update()
 
     def iter(self, it):
         try: