Simplify Windows DirectoryWatcher, reduce event buffer delay.

Author: davidmorgan

pkgs/watcher/CHANGELOG.md

@@ -3,6 +3,9 @@
 - Polling watchers now check file sizes as well as "last modified" times, so
   they are less likely to miss changes on platforms with low resolution
   timestamps.
+- `DirectoryWatcher` on Windows performance: reduce 100ms buffering of events
+  before reporting to 5ms, the larger buffer isn't needed for correctness after
+  the various fixes.
 - Bug fix: while listing directories skip symlinks that lead to a directory
   that has already been listed. This prevents a severe performance regression on
   MacOS and Linux when there are more than a few symlink loops.