www-Class for loading local texture is very slow

We just hit this problem as well with Unity 5.0.2 / Windows 7 x64 using WWW to load local image files using;

 var www = new WWW("file:///path/to/file");

Depending on the state of the network connection the local image load is either instant or Unity blocks and the image load takes 3-4secs. The test images are ~50k jpg's so they should load nearly instantly every time. The same applies for loading other content types, not just images.

We haven't fully tracked it down yet but using ProcessMonitor we can see that even loading a local file (using WWW with file:///) Unity appears to ask the OS/network stack some things (it loads dlls and does some other weirdness) but doesn't make an actual outgoing network connection, and then it loads the local file.

We noticed that if there is a gateway in the network settings but no internet connection Unity blocks for 3-4secs and then loads the local image ok. After unplugging the network, disabling the network stack, or updating the gateway (ie. a usual connected state or no connection) Unity loads the image immediately. It's a strange bug and sometimes seems dependent on whether a full connection or non-connection exists at the first request or not. Plugging/unplugging the network connection while the app is running also makes the images load immediately or with the blocking problem - nothing appears cached from Unity talking to the OS/network stack when making further WWW requests for local files.

The workaround is easy enough for our case - we simply load the local image via a byte array and load it into a texture;

 try {
   byte[] binaryImageData = File.ReadAllBytes(localImagePath);
   contentTexture.LoadImage(binaryImageData);
 }
 catch {...}