The Hidden Gems of .NET 10: Lesser-Known Features That Will Transform Your Development

by DeeDee Walsh, on Jul 12, 2025 12:07:03 PM

While everyone's talking about the sexy features in .NET 10 - C# 14's extension members, Blazor improvements, and performance boosts - there's a ton of lesser-known features that deserve your attention. These hidden gems might not make the keynote demos, but they'll impact your day-to-day development experience.

As we explore .NET 10 (currently in Preview 5), I'll show you the features that flew under the radar but pack a punch for productivity, performance, and code quality.

1. Certificate Management Gets a Modern Makeover {#certificate-management}

Remember the pain of finding certificates by thumbprint? .NET 10 quietly revolutionized this with support for finding certificates using hash algorithms other than SHA-1.

Before .NET 10:

// You were stuck with SHA-1 thumbprints
var store = new X509Store(StoreName.My, StoreLocation.CurrentUser);
store.Open(OpenFlags.ReadOnly);
var certificates = store.Certificates.Find(
    X509FindType.FindByThumbprint, 
    sha1Thumbprint, 
    false);

With .NET 10:

// Now you can use any hash algorithm!
var certificates = store.Certificates.Find(
    X509FindType.FindByThumbprint<SHA256>, 
    sha256Thumbprint, 
    false);

// Or even SHA-512 for the security conscious
var secureCerts = store.Certificates.Find(
    X509FindType.FindByThumbprint<SHA512>, 
    sha512Thumbprint, 
    false);

This seemingly small change has huge implications for security-conscious applications moving away from SHA-1.

2. Time-Related APIs That Actually Make Sense {#time-apis}

ISO week calculations have always been a pain. .NET 10 introduces ISOWeek.ToDateOnly(), making calendar operations surprisingly elegant.

// Converting ISO week to actual date - finally simple!
DateOnly date = ISOWeek.ToDateOnly(2025, 15, DayOfWeek.Monday);
int weekOfYear = ISOWeek.GetWeekOfYear(date);

// Perfect for business applications that work with week numbers
var quarterStart = ISOWeek.ToDateOnly(2025, 1, DayOfWeek.Monday);
var quarterEnd = ISOWeek.ToDateOnly(2025, 13, DayOfWeek.Friday);

But here's the real hidden gem: TimeSpan got a breaking change fix that solves LINQ compilation errors:

// This used to cause compilation errors in LINQ
var delays = new[] { 100, 200, 300 }
    .Select(ms => TimeSpan.FromMilliseconds(ms)) // Now works perfectly!
    .ToList();

// New overload for simple millisecond conversion
var simpleDelay = TimeSpan.FromMilliseconds(500);

// Explicit microsecond precision when needed
var preciseDelay = TimeSpan.FromMilliseconds(500, 750);

3. String Normalization Without the Memory Hit {#string-normalization}

This is a game-changer for performance-critical applications. .NET 10 adds span-based string normalization APIs:

// Old way - allocates new strings
string normalized = someString.Normalize(NormalizationForm.FormC);

// New way - works directly with spans!
Span<char> buffer = stackalloc char[1024];
ReadOnlySpan<char> input = "café".AsSpan();
int written = input.Normalize(buffer, NormalizationForm.FormC);

// Perfect for high-performance scenarios
public static bool AreEquivalent(ReadOnlySpan<char> a, ReadOnlySpan<char> b)
{
    Span<char> normalizedA = stackalloc char[a.Length * 2];
    Span<char> normalizedB = stackalloc char[b.Length * 2];
    
    int lenA = a.Normalize(normalizedA, NormalizationForm.FormC);
    int lenB = b.Normalize(normalizedB, NormalizationForm.FormC);
    
    return normalizedA[..lenA].SequenceEqual(normalizedB[..lenB]);
}

4. The Quiet Revolution in JIT Optimizations {#jit-optimizations}

While not visible in your code, these JIT improvements dramatically impact performance:

Array Interface Devirtualization

The JIT can now see through array interfaces, closing the 4x performance gap:

// This abstraction no longer carries a performance penalty!
public int Sum(IEnumerable<int> numbers)
{
    int sum = 0;
    foreach (var n in numbers) // JIT optimizes this like direct array access
    {
        sum += n;
    }
    return sum;
}

// Benchmark results:
// .NET 8:  100ms (with interface overhead)
// .NET 10: 25ms  (near-direct array performance)

Stack Allocation for Small Arrays

Small value-type arrays can now live on the stack:

public int Calculate()
{
    // This might be stack-allocated in .NET 10!
    int[] coefficients = new int[] { 1, 2, 3, 4 };
    return ProcessCoefficients(coefficients);
}

// The JIT recognizes the array doesn't escape and optimizes accordingly

Smarter Block Reordering

The JIT now uses the 3-opt heuristic from the Travelling Salesman Problem to optimize code layout:

// Your hot paths are now physically closer in memory
public void ProcessData(bool condition)
{
    if (condition) // JIT places this closer to subsequent code if it's hot
    {
        // Hot path operations
    }
    else
    {
        // Cold path moved further away
    }
}

5. SDK Improvements That Save Time and Space {#sdk-improvements}

Automatic Removal of Framework-Provided Packages

Your projects just got leaner:

<!-- In your .csproj -->
<PropertyGroup>
    <RemoveFrameworkProvidedPackages>true</RemoveFrameworkProvidedPackages>
</PropertyGroup>

Benefits:

✅ Faster builds (fewer packages to restore)
✅ Smaller deployment size
✅ Fewer false security warnings
✅ Cleaner dependency graphs

Native Tab Completion

The CLI now generates shell-specific completion scripts:

# Generate completions for your shell
dotnet complete --position 10 "dotnet bu"
# Returns: build, build-server

# Works with PowerShell, Bash, Zsh, and Fish!

6. Developer Productivity Enhancements {#developer-productivity}

Implicit Index Support in More Places

The ^ operator now works in more contexts:

public T Average<T>(T[] values) where T : INumber<T>
{
    T sum = T.Zero;
    foreach (var value in values)
    {
        sum += value; // Better optimization in .NET 10
    }
    return sum / T.CreateChecked(values.Length);
}

7. Debugging and Diagnostics: The Unsung Heroes {#debugging-diagnostics}

Enhanced StackTrace Information

Stack traces now include more context without performance penalty:

try
{
    ThrowHelper();
}
catch (Exception ex)
{
    // Stack traces now include generic type parameters
    // and better async method state information
    Console.WriteLine(ex.StackTrace);
}

ActivitySource Improvements

Better integration with OpenTelemetry:

private static readonly ActivitySource Source = new("MyApp", "1.0.0");

using var activity = Source.StartActivity("ProcessOrder", 
    ActivityKind.Internal,
    parentContext: default,
    tags: new[] { KeyValuePair.Create("order.id", orderId) },
    links: default,
    startTime: DateTimeOffset.UtcNow); // New: Explicit start time support

8. Performance Counters You Didn't Know You Needed {#performance-counters}

GC Region Information

New APIs expose GC region details:

// Get detailed GC memory information
var info = GC.GetMemoryInfo();
var regionCount = info.RegionCount; // New in .NET 10
var regionSize = info.RegionSizeBytes; // New in .NET 10

// Perfect for understanding memory fragmentation
Console.WriteLine($"GC using {regionCount} regions of {regionSize} bytes each");

Thread Pool Metrics

Better visibility into thread pool behavior:

// New ThreadPool.GetMetrics() API
var metrics = ThreadPool.GetMetrics();
Console.WriteLine($"Active threads: {metrics.ActiveThreadCount}");
Console.WriteLine($"Queued items: {metrics.QueuedItemCount}");
Console.WriteLine($"Completed items: {metrics.CompletedItemCount}");

9. Integration Improvements That Just Work {#integration-improvements}

HTTP/3 Performance Enhancements

While HTTP/3 support isn't new, .NET 10 includes hidden optimizations:

// Automatic connection coalescing for HTTP/3
var client = new HttpClient(new SocketsHttpHandler
{
    EnableMultipleHttp3Connections = true, // New option
    Http3ConnectionIdleTimeout = TimeSpan.FromMinutes(1)
});

Better Container Integration

Console apps can now create containers natively:

// In your .csproj
<PropertyGroup>
    <EnableSdkContainerSupport>true</EnableSdkContainerSupport>
    <ContainerImageFormat>oci</ContainerImageFormat> <!-- New: explicit format -->
</PropertyGroup>

Real-World Impact: A Case Study

Let's see how these hidden gems work together in a real scenario:

public class HighPerformanceProcessor
{
    private static readonly ActivitySource Telemetry = new("Processor", "1.0");
    
    public async Task<ProcessResult> ProcessDataAsync(ReadOnlyMemory<byte> data)
    {
        // Hidden gem: Better activity tracking
        using var activity = Telemetry.StartActivity("ProcessData", 
            startTime: DateTimeOffset.UtcNow);
        
        // Hidden gem: Stack-allocated arrays for small buffers
        int[] hashCodes = new int[4]; // Might be stack-allocated
        
        // Hidden gem: Span-based normalization
        Span<char> normalized = stackalloc char[1024];
        var text = Encoding.UTF8.GetString(data.Span);
        var normalizedLength = text.AsSpan().Normalize(normalized, 
            NormalizationForm.FormC);
        
        // Hidden gem: JIT optimizations make this fast
        var sum = ProcessArray(hashCodes);
        
        // Hidden gem: Better GC metrics
        var gcInfo = GC.GetMemoryInfo();
        activity?.SetTag("gc.regions", gcInfo.RegionCount);
        
        return new ProcessResult
        {
            Hash = sum,
            ProcessedAt = ISOWeek.GetWeekOfYear(DateOnly.FromDateTime(DateTime.Now))
        };
    }
    
    // Hidden gem: Array interface devirtualization
    private int ProcessArray(IEnumerable<int> values)
    {
        int result = 0;
        foreach (var value in values) // No virtualization overhead!
        {
            result ^= value;
        }
        return result;
    }
}

Why These Features Matter {#conclusion}

These hidden gems in .NET 10 represent the platform's maturity. While they might not grab headlines, they solve real problems developers face daily:

Performance Without Complexity: Features like array devirtualization and span-based APIs give you performance wins without code changes.
Developer Experience: Small improvements like better certificate management and time APIs reduce friction in common tasks.
Production Readiness: Enhanced diagnostics and metrics help you understand your application's behavior in production.
Future-Proofing: Support for new security standards (non-SHA1 certificates) and hardware features (AVX 10.2) ensures your applications stay current.

Getting Started

To experiment with these features:

# Install .NET 10 Preview
winget install Microsoft.DotNet.SDK.Preview

# Create a new project
dotnet new console -n Net10HiddenGems -f net10.0

# Enable preview features
# Add to your .csproj:
# <LangVersion>preview</LangVersion>
# <EnablePreviewFeatures>true</EnablePreviewFeatures>a

And Finally

The best features in .NET 10 aren't always the most obvious (and they don't always show up in the cool demos). But, start checking out .NET 10 now and you'll be ready to go when it ships in November 2025.

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