When dealing with massive directories containing 100,000+ files, Windows Explorer becomes a liability rather than a tool. The NTFS filesystem itself handles large directories well, but Explorer's caching mechanism and Shell extensions create severe performance bottlenecks. During my work with enterprise systems, I've seen Explorer consume 4GB+ RAM just trying to display such directories.

The standard approaches have critical flaws:

del /f/q/s *.* > nul
rmdir /s/q foldername

These commands process files sequentially and perform redundant ACL checks. On NTFS volumes, they trigger excessive journaling operations. The MFT (Master File Table) becomes a choke point.

This PowerShell method leverages parallel processing and direct filesystem access:

$folder = "C:\\problem_directory"
$files = [System.IO.Directory]::EnumerateFiles($folder, "*", "AllDirectories")
$files | ForEach-Object -Parallel {
    [System.IO.File]::Delete($_)
} -ThrottleLimit 16

Key advantages:

• Bypasses Shell overhead
• Uses async I/O
• Configurable thread count
• Progress tracking capability

For mission-critical systems where downtime isn't an option, consider this C# implementation using Win32 API:

[DllImport("kernel32.dll", CharSet = CharSet.Unicode)]
static extern bool DeleteFile(string lpFileName);

void PurgeDirectory(string path) {
    foreach (var file in Directory.EnumerateFiles(path, "*", SearchOption.AllDirectories)) {
        DeleteFile(@"\\?\" + file); // UNC path prefix bypasses MAX_PATH limitation
    }
    Directory.Delete(path, true);
}

For the temp file scenario mentioned in the original post:

// C# example of robust temp file handling
using (var tempFile = new FileStream(Path.GetTempFileName(), 
    FileMode.Create, 
    FileAccess.ReadWrite, 
    FileShare.Delete, 
    4096, 
    FileOptions.DeleteOnClose | FileOptions.Asynchronous)) 
{
    // Work with temp file here
} // Auto-deletes on disposal

For sysadmins managing multiple systems:

1. Create a RamDisk for temp directories
2. Implement filesystem minifilter drivers
3. Use PowerShell DSC for cleanup automation

Windows Explorer's infamous memory bloating during large file operations isn't just annoying - it's a systemic limitation of the legacy Windows file management architecture. When dealing with 100,000+ files, even command-line tools like DEL and RMDIR often fail due to:

• File handle leaks from interrupted operations
• NTFS permission inheritance bottlenecks
• Path length limitations (MAX_PATH = 260 chars)
• Metadata caching overhead

After battling this across multiple client systems, here are the most effective approaches:

@echo off
setlocal enabledelayedexpansion
for /f "delims=" %%i in ('dir /a-d /b') do (
  del /f /q "%%i"
  if !errorlevel! neq 0 (
    echo Failed: %%i >> deletion_log.txt
  )
)

For more robust handling, consider these alternatives:

The secret sauce lies in bypassing the shell namespace. Here's a C# example using kernel32:

[DllImport("kernel32.dll", CharSet=CharSet.Unicode)]
static extern bool DeleteFile(string lpFileName);

void PurgeDirectory(string path) {
  var files = Directory.EnumerateFiles(path, "*", SearchOption.AllDirectories);
  Parallel.ForEach(files, file => {
    if (!DeleteFile(file)) {
      File.SetAttributes(file, FileAttributes.Normal);
      DeleteFile(file);
    }
  });
}

For applications generating temporary files:

1. Implement named pipes instead of physical files
2. Use RAM disks for transient storage
3. Configure temp directory with isolated permissions
4. Schedule periodic cleanup via Task Scheduler

The ultimate solution is replacing legacy file handling with modern storage APIs, but until then, these techniques will keep your systems running.