Performance analysis: Document inefficiencies and fix resource leaks

[Copilot]

Analyzed codebase for performance bottlenecks. Documented 60+ inefficiencies across 7 categories without changing functional behavior. Fixed critical MDL resource leaks in file copy operations.

Performance Issues Documented

High impact:

• BCrypt algorithm providers opened/closed per hash operation instead of cached at module level
• Memory allocated/freed on every enumeration loop iteration (Registry, system handles)

Medium impact:

• 60+ instances of RtlZeroMemory immediately before buffer is overwritten
• NonPagedPool used at PASSIVE_LEVEL where PagedPool is appropriate
• Linear memory growth (+4096) instead of using returned required size

Low impact:

• 16KB file I/O buffers where 64KB would reduce syscalls

Bug Fixes

Fixed MDL leaks in KfcCopyFile:

// Before: MDL never freed
PMDL mdl = IoAllocateMdl(buffer, size, FALSE, TRUE, nullptr);
if (error) {
    ExFreePoolWithTag(buffer, TAG);
    return error;  // MDL leaked
}

// After: MDL freed on all paths
PMDL mdl = IoAllocateMdl(buffer, size, FALSE, TRUE, nullptr);
if (!mdl) {
    ExFreePoolWithTag(buffer, TAG);
    return STATUS_INSUFFICIENT_RESOURCES;
}
if (error) {
    IoFreeMdl(mdl);
    ExFreePoolWithTag(buffer, TAG);
    return error;
}

Documentation

• PERFORMANCE.md - Technical analysis with file locations, line numbers, and code examples
• PERFORMANCE_SUMMARY.md - Executive summary with prioritization and implementation roadmap
• Inline comments at key locations reference detailed documentation

Recommendations can be implemented separately based on priority. All changes maintain compatibility with Windows XP+ across x86/x64/ARM/ARM64.

Original prompt

Identify and suggest improvements to slow or inefficient code

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