Don't cache path Context based on cwd, as cwd involves a system-call to compute.

pkg/path/lib/src/context.dart

Index: pkg/path/lib/src/context.dart
diff --git a/pkg/path/lib/src/context.dart b/pkg/path/lib/src/context.dart
index 823e0c28402d83b6b7db1e0f305174be5ac303f7..f28aad53589137b632101d15953a713d222df269 100644
--- a/pkg/path/lib/src/context.dart
+++ b/pkg/path/lib/src/context.dart
@@ -23,12 +23,8 @@ class Context {
   /// On the browser, [style] defaults to [Style.url] and [current] defaults to
   /// the current URL.
   factory Context({Style style, String current}) {
-    if (current == null) {
-      if (style == null) {
-        current = p.current;
-      } else {
-        current = ".";
-      }
+    if (current == null && style != null) {
+      current = ".";
     }
 
     if (style == null) {
@@ -41,13 +37,17 @@ class Context {
     return new Context._(style, current);
   }
 
-  Context._(this.style, this.current);
+  Context._(this.style, this._current);
 
   /// The style of path that this context works with.
   final InternalStyle style;
 
+  /// The current given when Context was created. If null, current should be

[Bob Nystrom, 2014/07/30 16:15:08]

"current" -> "current directory".

"should be" -> "is".

[Anders Johnsen, 2014/07/31 06:19:42]

Done.

+  /// evaluated from 'p.current'.
+  final String _current;
+
   /// The current directory that relative paths will be relative to.

[Bob Nystrom, 2014/07/30 16:15:08]

"will be" -> "are".

[Anders Johnsen, 2014/07/31 06:19:42]

Done.

-  final String current;
+  String get current => _current != null ? _current : p.current;
 
   /// Gets the path separator for the context's [style]. On Mac and Linux,
   /// this is `/`. On Windows, it's `\`.