Like many SDKs, Dart/Flutter consist of hundreds of thousands of files. This easily becomes a performance problem on Windows, especially with AV solutions like Windows Defender, and results on slow code completion, analysis and generally sluggish performance of tools, e.g. in Visual Studio Code.

One solution to this problem is to disable the AV solution or just exclude the directories containing the SDKs. We will skip the explanation why this is generally a bad idea, but there is an alternative solution, namely Windows 11’s new Dev Drives, basically a VHDX using ReFs. Windows Defender does use a different mode of scanning files for all DevDrives, so this is a neat solution.

We just need to move all the Flutter/Dart SDK files to the newly created DevDrive (e.g. D:\Flutter), but that still does not yield the expected results. This is because the analyzer and public cache are still by default stored in the user’s home directories.

Moving these to the DevDrive significantly speeds up the analyzer, compilation, and all other tasks. These Environment Variables can be used to specify the new location of the folders:

ANALYZER_STATE_LOCATION_OVERRIDE	D:\.dart-Server
PUB_CACHE	D:\.pub-cache
GRADLE_USER_HOME	D:\.gradle

There seems to be a lot of confusion amongst developers how to get persistible permissions when using the SAF. Wasted some hours on this, so it is worth a note here.

To get the average file open dialog using the SAF, one could do this:

Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
intent.addCategory(Intent.CATEGORY_OPENABLE);
intent.setType("*/*");
startActivityForResult(i, 0);

That works perfectly fine, but after a reboot, the permissions are gone, and opening the same file (without opening the dialog again) will fail. There are lots of resources on the Internet that tell developers to add some arguments when calling the Intent. This is wrong! Passing these to the intent is completely useless:

intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION); // Don't do this
intent.addFlags(Intent.FLAG_GRANT_WRITE_URI_PERMISSION); // Also no!
intent.addFlags(Intent.FLAG_GRANT_PERSISTABLE_URI_PERMISSION); // NO!

Instead, a single call to takePersistableUriPermission will retain permissions even after a reboot:

protected void onPropertyRequestResult(int propertyRequestCode, int resultCode, Intent data) {
    getContentResolver().takePersistableUriPermission(data.getData(), Intent.FLAG_GRANT_READ_URI_PERMISSION | Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
}