diff --git a/core/src/main/scala-2.13+/cats/instances/arraySeq.scala b/core/src/main/scala-2.13+/cats/instances/arraySeq.scala
index 4ced92e1cb..d314e7b5eb 100644
--- a/core/src/main/scala-2.13+/cats/instances/arraySeq.scala
+++ b/core/src/main/scala-2.13+/cats/instances/arraySeq.scala
@@ -104,7 +104,7 @@ private[cats] object ArraySeqInstances {
       def traverse[G[_], A, B](fa: ArraySeq[A])(f: A => G[B])(implicit G: Applicative[G]): G[ArraySeq[B]] =
         G match {
           case x: StackSafeMonad[G] =>
-            x.map(Traverse.traverseDirectly(Vector.newBuilder[B])(fa.iterator)(f)(x))(_.to(ArraySeq.untagged))
+            x.map(Traverse.traverseDirectly(fa.iterator)(f)(x))(_.to(ArraySeq.untagged))
           case _ =>
             G.map(Chain.traverseViaChain(fa)(f))(_.iterator.to(ArraySeq.untagged))
 
@@ -233,7 +233,7 @@ private[cats] object ArraySeqInstances {
       )(f: (A) => G[Option[B]])(implicit G: Applicative[G]): G[ArraySeq[B]] =
         G match {
           case x: StackSafeMonad[G] =>
-            x.map(TraverseFilter.traverseFilterDirectly(Vector.newBuilder[B])(fa.iterator)(f)(x))(
+            x.map(TraverseFilter.traverseFilterDirectly(fa.iterator)(f)(x))(
               _.to(ArraySeq.untagged)
             )
           case _ =>
diff --git a/core/src/main/scala/cats/Traverse.scala b/core/src/main/scala/cats/Traverse.scala
index fe1e62683f..563d259ae3 100644
--- a/core/src/main/scala/cats/Traverse.scala
+++ b/core/src/main/scala/cats/Traverse.scala
@@ -25,7 +25,6 @@ import cats.data.State
 import cats.data.StateT
 import cats.kernel.compat.scalaVersionSpecific._
 import cats.StackSafeMonad
-import scala.collection.mutable
 
 /**
  * Traverse, also known as Traversable.
@@ -287,21 +286,16 @@ object Traverse {
   @deprecated("Use cats.syntax object imports", "2.2.0")
   object nonInheritedOps extends ToTraverseOps
 
-  private[cats] def traverseDirectly[Coll[x] <: IterableOnce[x], G[_], A, B](
-    builder: mutable.Builder[B, Coll[B]]
-  )(fa: IterableOnce[A])(f: A => G[B])(implicit G: StackSafeMonad[G]): G[Coll[B]] = {
-    val size = fa.knownSize
-    if (size >= 0) {
-      builder.sizeHint(size)
-    }
-    G.map(fa.iterator.foldLeft(G.pure(builder)) { case (accG, a) =>
+  private[cats] def traverseDirectly[G[_], A, B](
+    fa: IterableOnce[A]
+  )(f: A => G[B])(implicit G: StackSafeMonad[G]): G[Vector[B]] = {
+    fa.iterator.foldLeft(G.pure(Vector.empty[B])) { case (accG, a) =>
       G.flatMap(accG) { acc =>
-        G.map(f(a)) { a =>
-          acc += a
-          acc
+        G.map(f(a)) { b =>
+          acc.appended(b)
         }
       }
-    })(_.result())
+    }
   }
 
   private[cats] def traverse_Directly[G[_], A, B](
diff --git a/core/src/main/scala/cats/TraverseFilter.scala b/core/src/main/scala/cats/TraverseFilter.scala
index 2cfa2145cb..515e005936 100644
--- a/core/src/main/scala/cats/TraverseFilter.scala
+++ b/core/src/main/scala/cats/TraverseFilter.scala
@@ -25,7 +25,6 @@ import cats.data.State
 import cats.kernel.compat.scalaVersionSpecific._
 
 import scala.collection.immutable.{IntMap, TreeSet}
-import scala.collection.mutable
 
 /**
  * `TraverseFilter`, also known as `Witherable`, represents list-like structures
@@ -205,21 +204,17 @@ object TraverseFilter {
   @deprecated("Use cats.syntax object imports", "2.2.0")
   object nonInheritedOps extends ToTraverseFilterOps
 
-  private[cats] def traverseFilterDirectly[Coll[x] <: IterableOnce[x], G[_], A, B](
-    builder: mutable.Builder[B, Coll[B]]
-  )(fa: IterableOnce[A])(f: A => G[Option[B]])(implicit G: StackSafeMonad[G]): G[Coll[B]] = {
-    val size = fa.knownSize
-    if (size >= 0) {
-      builder.sizeHint(size)
-    }
-    G.map(fa.iterator.foldLeft(G.pure(builder)) { case (bldrG, a) =>
-      G.flatMap(bldrG) { bldr =>
+  private[cats] def traverseFilterDirectly[G[_], A, B](
+    fa: IterableOnce[A]
+  )(f: A => G[Option[B]])(implicit G: StackSafeMonad[G]): G[Vector[B]] = {
+    fa.iterator.foldLeft(G.pure(Vector.empty[B])) { case (bldrG, a) =>
+      G.flatMap(bldrG) { acc =>
         G.map(f(a)) {
-          case Some(b) => bldr += b
-          case None    => bldr
+          case Some(b) => acc.appended(b)
+          case None    => acc
         }
       }
-    })(_.result())
+    }
   }
 
 }
diff --git a/core/src/main/scala/cats/data/Chain.scala b/core/src/main/scala/cats/data/Chain.scala
index 4fe4ec0cbe..1c55618aab 100644
--- a/core/src/main/scala/cats/data/Chain.scala
+++ b/core/src/main/scala/cats/data/Chain.scala
@@ -1243,7 +1243,7 @@ sealed abstract private[data] class ChainInstances extends ChainInstances1 {
         else
           G match {
             case x: StackSafeMonad[G] =>
-              x.map(Traverse.traverseDirectly(List.newBuilder[B])(fa.iterator)(f)(x))(Chain.fromSeq(_))
+              x.map(Traverse.traverseDirectly(fa.iterator)(f)(x))(Chain.fromSeq(_))
             case _ =>
               traverseViaChain {
                 val as = collection.mutable.ArrayBuffer[A]()
@@ -1372,7 +1372,7 @@ sealed abstract private[data] class ChainInstances extends ChainInstances1 {
       else
         G match {
           case x: StackSafeMonad[G] =>
-            G.map(TraverseFilter.traverseFilterDirectly(List.newBuilder[B])(fa.iterator)(f)(x))(Chain.fromSeq(_))
+            G.map(TraverseFilter.traverseFilterDirectly(fa.iterator)(f)(x))(Chain.fromSeq(_))
           case _ =>
             traverseFilterViaChain {
               val as = collection.mutable.ArrayBuffer[A]()
diff --git a/core/src/main/scala/cats/instances/list.scala b/core/src/main/scala/cats/instances/list.scala
index 2b18ee6810..eaeb6e298e 100644
--- a/core/src/main/scala/cats/instances/list.scala
+++ b/core/src/main/scala/cats/instances/list.scala
@@ -122,7 +122,7 @@ trait ListInstances extends cats.kernel.instances.ListInstances {
         if (fa.isEmpty) G.pure(Nil)
         else
           G match {
-            case x: StackSafeMonad[G] => Traverse.traverseDirectly[List, G, A, B](ListBuffer.empty[B])(fa)(f)(x)
+            case x: StackSafeMonad[G] => G.map(Traverse.traverseDirectly[G, A, B](fa)(f)(x))(_.toList)
             case _ =>
               G.map(Chain.traverseViaChain {
                 val as = collection.mutable.ArrayBuffer[A]()
@@ -320,7 +320,7 @@ private[instances] trait ListInstancesBinCompat0 {
       if (fa.isEmpty) G.pure(Nil)
       else
         G match {
-          case x: StackSafeMonad[G] => TraverseFilter.traverseFilterDirectly(List.newBuilder[B])(fa)(f)(x)
+          case x: StackSafeMonad[G] => x.map(TraverseFilter.traverseFilterDirectly(fa)(f)(x))(_.toList)
           case _ =>
             G.map(Chain.traverseFilterViaChain {
               val as = collection.mutable.ArrayBuffer[A]()
diff --git a/core/src/main/scala/cats/instances/queue.scala b/core/src/main/scala/cats/instances/queue.scala
index 75aaf32a9d..fd7313f4c4 100644
--- a/core/src/main/scala/cats/instances/queue.scala
+++ b/core/src/main/scala/cats/instances/queue.scala
@@ -122,7 +122,8 @@ trait QueueInstances extends cats.kernel.instances.QueueInstances {
         if (fa.isEmpty) G.pure(Queue.empty[B])
         else
           G match {
-            case x: StackSafeMonad[G] => Traverse.traverseDirectly(Queue.newBuilder[B])(fa)(f)(x)
+            case x: StackSafeMonad[G] =>
+              G.map(Traverse.traverseDirectly(fa)(f)(x))(catsStdInstancesForQueue.fromIterableOnce(_))
             case _ =>
               G.map(Chain.traverseViaChain {
                 val as = collection.mutable.ArrayBuffer[A]()
@@ -239,7 +240,8 @@ private object QueueInstances {
       if (fa.isEmpty) G.pure(Queue.empty[B])
       else
         G match {
-          case x: StackSafeMonad[G] => TraverseFilter.traverseFilterDirectly(Queue.newBuilder[B])(fa)(f)(x)
+          case x: StackSafeMonad[G] =>
+            x.map(TraverseFilter.traverseFilterDirectly(fa)(f)(x))(catsStdTraverseFilterForQueue.fromIterableOnce(_))
           case _ =>
             G.map(Chain.traverseFilterViaChain {
               val as = collection.mutable.ArrayBuffer[A]()
diff --git a/core/src/main/scala/cats/instances/seq.scala b/core/src/main/scala/cats/instances/seq.scala
index 005139d6c2..f6ea076921 100644
--- a/core/src/main/scala/cats/instances/seq.scala
+++ b/core/src/main/scala/cats/instances/seq.scala
@@ -129,7 +129,7 @@ trait SeqInstances extends cats.kernel.instances.SeqInstances {
       final override def traverse[G[_], A, B](fa: Seq[A])(f: A => G[B])(implicit G: Applicative[G]): G[Seq[B]] =
         G match {
           case x: StackSafeMonad[G] =>
-            Traverse.traverseDirectly(Seq.newBuilder[B])(fa)(f)(x)
+            x.map(Traverse.traverseDirectly(fa)(f)(x))(_.toSeq)
           case _ =>
             G.map(Chain.traverseViaChain(fa.toIndexedSeq)(f))(_.toVector)
         }
@@ -210,7 +210,7 @@ trait SeqInstances extends cats.kernel.instances.SeqInstances {
 
     def traverseFilter[G[_], A, B](fa: Seq[A])(f: (A) => G[Option[B]])(implicit G: Applicative[G]): G[Seq[B]] =
       G match {
-        case x: StackSafeMonad[G] => TraverseFilter.traverseFilterDirectly(Seq.newBuilder[B])(fa)(f)(x)
+        case x: StackSafeMonad[G] => x.map(TraverseFilter.traverseFilterDirectly(fa)(f)(x))(_.toSeq)
         case _ =>
           G.map(Chain.traverseFilterViaChain(fa.toIndexedSeq)(f))(_.toVector)
       }
diff --git a/core/src/main/scala/cats/instances/vector.scala b/core/src/main/scala/cats/instances/vector.scala
index d47d5f010a..9395374bda 100644
--- a/core/src/main/scala/cats/instances/vector.scala
+++ b/core/src/main/scala/cats/instances/vector.scala
@@ -126,7 +126,7 @@ trait VectorInstances extends cats.kernel.instances.VectorInstances {
 
       final override def traverse[G[_], A, B](fa: Vector[A])(f: A => G[B])(implicit G: Applicative[G]): G[Vector[B]] =
         G match {
-          case x: StackSafeMonad[G] => Traverse.traverseDirectly(Vector.newBuilder[B])(fa)(f)(x)
+          case x: StackSafeMonad[G] => Traverse.traverseDirectly(fa)(f)(x)
           case _                    => G.map(Chain.traverseViaChain(fa)(f))(_.toVector)
         }
 
@@ -271,7 +271,7 @@ private[instances] trait VectorInstancesBinCompat0 {
 
     def traverseFilter[G[_], A, B](fa: Vector[A])(f: (A) => G[Option[B]])(implicit G: Applicative[G]): G[Vector[B]] =
       G match {
-        case x: StackSafeMonad[G] => TraverseFilter.traverseFilterDirectly(Vector.newBuilder[B])(fa)(f)(x)
+        case x: StackSafeMonad[G] => TraverseFilter.traverseFilterDirectly(fa)(f)(x)
         case _ =>
           G.map(Chain.traverseFilterViaChain(fa)(f))(_.toVector)
       }