diff --git a/lib/Sema/CSBindings.cpp b/lib/Sema/CSBindings.cpp
index 2ee71759d2bea..1fb8acda986c1 100644
--- a/lib/Sema/CSBindings.cpp
+++ b/lib/Sema/CSBindings.cpp
@@ -1232,6 +1232,36 @@ bool BindingSet::isViable(PotentialBinding &binding, bool isTransitive) {
   return true;
 }
 
+static bool hasConversions(Type type) {
+  if (type->isAnyHashable() || type->isDouble() || type->isCGFloat())
+    return true;
+
+  if (type->getAnyPointerElementType())
+    return true;
+
+  if (auto *structTy = type->getAs<BoundGenericStructType>()) {
+    if (auto eltTy = structTy->isArrayType()) {
+      return hasConversions(eltTy);
+    } else if (auto pair = ConstraintSystem::isDictionaryType(structTy)) {
+      return hasConversions(pair->second);
+    } else if (auto eltTy = ConstraintSystem::isSetType(structTy)) {
+      return hasConversions(*eltTy);
+    }
+
+    return false;
+  }
+
+  if (auto *enumTy = type->getAs<BoundGenericEnumType>()) {
+    if (enumTy->getOptionalObjectType())
+      return true;
+
+    return false;
+  }
+
+  return !(type->is<StructType>() || type->is<EnumType>() ||
+           type->is<BuiltinType>() || type->is<ArchetypeType>());
+}
+
 bool BindingSet::favoredOverDisjunction(Constraint *disjunction) const {
   if (isHole())
     return false;
@@ -1240,30 +1270,10 @@ bool BindingSet::favoredOverDisjunction(Constraint *disjunction) const {
         if (binding.Kind == AllowedBindingKind::Supertypes)
           return false;
 
-        auto type = binding.BindingType;
-
         if (CS.shouldAttemptFixes())
           return false;
 
-        if (type->isAnyHashable() || type->isDouble() || type->isCGFloat())
-          return false;
-
-        {
-          PointerTypeKind pointerKind;
-          if (type->getAnyPointerElementType(pointerKind)) {
-            switch (pointerKind) {
-            case PTK_UnsafeRawPointer:
-            case PTK_UnsafeMutableRawPointer:
-              return false;
-
-            default:
-              break;
-            }
-          }
-        }
-
-        return type->is<StructType>() || type->is<EnumType>() ||
-               type->is<BuiltinType>();
+        return !hasConversions(binding.BindingType);
       })) {
     // Result type of subscript could be l-value so we can't bind it early.
     if (!TypeVar->getImpl().isSubscriptResultType() &&
diff --git a/validation-test/Sema/type_checker_perf/fast/array_concatenation.swift b/validation-test/Sema/type_checker_perf/fast/array_concatenation.swift
new file mode 100644
index 0000000000000..1ce9d4293dc49
--- /dev/null
+++ b/validation-test/Sema/type_checker_perf/fast/array_concatenation.swift
@@ -0,0 +1,30 @@
+// RUN: %target-typecheck-verify-swift -solver-disable-shrink
+
+// Self-contained test case
+protocol P1 {}; func f<T: P1>(_: T, _: T) -> T { fatalError() }
+protocol P2 {}; func f<T: P2>(_: T, _: T) -> T { fatalError() }
+protocol P3 {}; func f<T: P3>(_: T, _: T) -> T { fatalError() }
+protocol P4 {}; func f<T: P4>(_: T, _: T) -> T { fatalError() }
+
+func f<T>(_: Array<T>, _: Array<T>) -> Array<T> { fatalError() }
+
+let fn1: (_, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _) -> Array<Int> = {
+  f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f($0, $1), $2), $3), $4), $5), $6), $7), $8), $9), $10), $11), $12), $13), $14), $15), $16), $17), $18), $19)
+}
+
+let fn2: (_, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _) -> Array<Int> = {
+  f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f([$0], [$1]), [$2]), [$3]), [$4]), [$5]), [$6]), [$7]), [$8]), [$9]), [$10]), [$11]), [$12]), [$13]), [$14]), [$15]), [$16]), [$17]), [$18]), [$19])
+}
+
+let x1: Array<Int> = f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f([0], [0]), [0]), [0]), [0]), [0]), [0]), [0]), [0]), [0]), [0]), [0]), [0]), [0]), [0]), [0]), [0]), [0]), [0]), [0])
+
+// Same setup with standard library operator
+let fn3: (_, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _) -> Array<Int> = {
+  $0 + $1 + $2 + $3 + $4 + $5 + $6 + $7 + $8 + $9 + $10 + $11 + $12 + $13 + $14 + $15 + $16 + $17 + $18 + $19
+}
+
+let fn4: (_, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _) -> Array<Int> = {
+  [$0] + [$1] + [$2] + [$3] + [$4] + [$5] + [$6] + [$7] + [$8] + [$9] + [$10] + [$11] + [$12] + [$13] + [$14] + [$15] + [$16] + [$17] + [$18] + [$19]
+}
+
+let x2: Array<Int> = [0] + [0] + [0] + [0] + [0] + [0] + [0] + [0] + [0] + [0] + [0] + [0] + [0] + [0] + [0] + [0] + [0] + [0] + [0] + [0]
diff --git a/validation-test/Sema/type_checker_perf/slow/mixed_string_array_addition.swift b/validation-test/Sema/type_checker_perf/fast/mixed_string_array_addition.swift
similarity index 76%
rename from validation-test/Sema/type_checker_perf/slow/mixed_string_array_addition.swift
rename to validation-test/Sema/type_checker_perf/fast/mixed_string_array_addition.swift
index aa0c3979b5ef2..75c7d1050eb4d 100644
--- a/validation-test/Sema/type_checker_perf/slow/mixed_string_array_addition.swift
+++ b/validation-test/Sema/type_checker_perf/fast/mixed_string_array_addition.swift
@@ -3,7 +3,6 @@
 func method(_ arg: String, body: () -> [String]) {}
 
 func test(str: String, properties: [String]) {
-  // expected-error@+1 {{the compiler is unable to type-check this expression in reasonable time}}
   method(str + "" + str + "") {
     properties.map { param in
       "" + param + "" + param + "" + param + ""