diff --git a/PerfectNumbers.Core/PrimeOrderCalculator.Cpu.cs b/PerfectNumbers.Core/PrimeOrderCalculator.Cpu.cs
index 835b80d..fa20429 100644
--- a/PerfectNumbers.Core/PrimeOrderCalculator.Cpu.cs
+++ b/PerfectNumbers.Core/PrimeOrderCalculator.Cpu.cs
@@ -720,6 +720,63 @@ internal static partial class PrimeOrderCalculator
 		return isPrime;
 	}
 
+
+	[ThreadStatic]
+	private static Dictionary<ulong, bool>? _partialFactorPrimalityCache;
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	private static void ResetPartialFactorPrimalityCache()
+	{
+		Dictionary<ulong, bool>? cache = _partialFactorPrimalityCache;
+		if (cache is not null && cache.Count > 0)
+		{
+			cache.Clear();
+		}
+	}
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	private static Dictionary<ulong, bool> GetPartialFactorPrimalityCache()
+	{
+		Dictionary<ulong, bool>? cache = _partialFactorPrimalityCache;
+		if (cache is null)
+		{
+			cache = ThreadStaticPools.RentUlongBoolDictionary(4);
+			_partialFactorPrimalityCache = cache;
+		}
+
+		return cache;
+	}
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	private static bool EvaluatePrimalityPartialFactor(ulong candidate)
+	{
+		if (TryGetCachedPrimality(candidate, out bool cached))
+		{
+			return cached;
+		}
+
+		ulong globalCacheLimit = (ulong)PerfectNumberConstants.MaxQForDivisorCycles;
+		if (candidate > globalCacheLimit)
+		{
+			Dictionary<ulong, bool>? cache = _partialFactorPrimalityCache;
+			if (cache is not null && cache.TryGetValue(candidate, out bool cachedValue))
+			{
+				return cachedValue;
+			}
+		}
+
+		bool isPrime = Open.Numeric.Primes.Prime.Numbers.IsPrime(candidate);
+		CachePrimalityResult(candidate, isPrime);
+
+		if (candidate > globalCacheLimit)
+		{
+			Dictionary<ulong, bool> cache = GetPartialFactorPrimalityCache();
+			cache[candidate] = isPrime;
+		}
+
+		return isPrime;
+	}
+
 	private static PartialFactorResult PartialFactor(ulong value, in PrimeOrderSearchConfig config)
 	{
 		if (value <= 1UL)
@@ -757,26 +814,7 @@ internal static partial class PrimeOrderCalculator
 		Stack<ulong>? compositeStack = null;
 		PartialFactorResult result;
 
-		Dictionary<ulong, bool>? localPrimalityCache = null;
-
-		bool EvaluatePrimality(ulong candidate)
-		{
-			Dictionary<ulong, bool>? cache = localPrimalityCache;
-			if (cache is not null && cache.TryGetValue(candidate, out bool cachedValue))
-			{
-				return cachedValue;
-			}
-
-			bool computed = GetOrComputePrimality(candidate);
-			if (!computed)
-			{
-				cache ??= ThreadStaticPools.RentUlongBoolDictionary(4);
-				cache[candidate] = false;
-				localPrimalityCache = cache;
-			}
-
-			return computed;
-		}
+		ResetPartialFactorPrimalityCache();
 
 		if (!gpuFactored)
 		{
@@ -842,7 +880,7 @@ internal static partial class PrimeOrderCalculator
 					// 	continue;
 					// }
 
-					bool isPrime = EvaluatePrimality(composite);
+					bool isPrime = EvaluatePrimalityPartialFactor(composite);
 
 					if (isPrime)
 					{
@@ -889,7 +927,7 @@ internal static partial class PrimeOrderCalculator
 				continue;
 			}
 
-			bool isPrime = EvaluatePrimality(composite);
+			bool isPrime = EvaluatePrimalityPartialFactor(composite);
 
 			if (isPrime)
 			{
@@ -915,7 +953,7 @@ internal static partial class PrimeOrderCalculator
 		}
 		else
 		{
-			cofactorIsPrime = EvaluatePrimality(cofactor);
+			cofactorIsPrime = EvaluatePrimalityPartialFactor(cofactor);
 		}
 
 		ArrayPool<FactorEntry> pool = ThreadStaticPools.FactorEntryPool;
@@ -989,10 +1027,6 @@ internal static partial class PrimeOrderCalculator
 		// ThreadStaticPools.UlongPool.Return(primeSlotsArray);
 		// ThreadStaticPools.IntPool.Return(exponentSlotsArray);
 
-		if (localPrimalityCache is not null)
-		{
-			ThreadStaticPools.ReturnUlongBoolDictionary(localPrimalityCache);
-		}
 
 		if (counts is not null)
 		{