Improve ImmutableArrayExtensions.SequenceEqual

src/libraries/System.Collections.Immutable/src/System/Linq/ImmutableArrayExtensions.cs

@@ -189,9 +189,32 @@ public static bool SequenceEqual<TDerived, TBase>(this ImmutableArray<TBase> imm
         {
             Requires.NotNull(items, nameof(items));
 
+            int i = 0;
+            if (items.TryGetCount(out var count))
+            {
+                if (immutableArray.Length != count)
+                {
+                    return false;
+                }
+
+                if (items is IList<TDerived> itemList)
+                {
+                    comparer ??= EqualityComparer<TBase>.Default;
+
+                    for (i = 0; i < count; i++)
+                    {
+                        if (!comparer.Equals(immutableArray[i], itemList[i]))
+                        {
+                            return false;
+                        }
+                    }
+
+                    return true;
+                }
+            }
+
             comparer ??= EqualityComparer<TBase>.Default;
 
-            int i = 0;
             int n = immutableArray.Length;
             foreach (TDerived item in items)
             {