perf: improve applyOrdering by avoid call to GetByCurrentId

This shaves of 14 seconds (one third) of the execution time for a
kustomization tree with 4000 documents, from 40.68s to 27.41s

            0     0%  5.44%     18.42s 40.56%  sigs.k8s.io/kustomize/api/krusty.(*Kustomizer).applySortOrder
            0     0%  5.44%     18.40s 40.52%  sigs.k8s.io/kustomize/api/internal/builtins.applyOrdering
before

    (pprof) top20 -cum
    Showing nodes accounting for 5.85s, 12.88% of 45.41s total
    Dropped 622 nodes (cum <= 0.23s)
    Showing top 20 nodes out of 157
        flat  flat%   sum%        cum   cum%
            0     0%     0%     40.68s 89.58%  github.com/spf13/cobra.(*Command).Execute
            0     0%     0%     40.68s 89.58%  github.com/spf13/cobra.(*Command).ExecuteC
            0     0%     0%     40.68s 89.58%  github.com/spf13/cobra.(*Command).execute
            0     0%     0%     40.68s 89.58%  main.main
            0     0%     0%     40.68s 89.58%  runtime.main
            0     0%     0%     40.68s 89.58%  sigs.k8s.io/kustomize/kustomize/v5/commands/build.NewCmdBuild.func1
            0     0%     0%     40.12s 88.35%  sigs.k8s.io/kustomize/api/krusty.(*Kustomizer).Run
        0.51s  1.12%  1.12%     33.20s 73.11%  sigs.k8s.io/kustomize/api/resource.(*Resource).CurId
            0     0%  1.12%     26.95s 59.35%  sigs.k8s.io/kustomize/api/resmap.(*resWrangler).GetMatchingResourcesByCurrentId
        0.35s  0.77%  1.89%     26.95s 59.35%  sigs.k8s.io/kustomize/api/resmap.(*resWrangler).filteredById
        0.07s  0.15%  2.05%     25.53s 56.22%  sigs.k8s.io/kustomize/api/resmap.GetCurrentId
            0     0%  2.05%     21.68s 47.74%  sigs.k8s.io/kustomize/api/internal/target.(*KustTarget).MakeCustomizedResMap (inline)
            0     0%  2.05%     21.68s 47.74%  sigs.k8s.io/kustomize/api/internal/target.(*KustTarget).makeCustomizedResMap
        0.54s  1.19%  3.24%     19.75s 43.49%  sigs.k8s.io/kustomize/api/resource.(*Resource).GetGvk (inline)
            1s  2.20%  5.44%     19.21s 42.30%  sigs.k8s.io/kustomize/kyaml/resid.GvkFromNode
            0     0%  5.44%     18.42s 40.56%  sigs.k8s.io/kustomize/api/internal/builtins.(*SortOrderTransformerPlugin).Transform
            0     0%  5.44%     18.42s 40.56%  sigs.k8s.io/kustomize/api/krusty.(*Kustomizer).applySortOrder
            0     0%  5.44%     18.40s 40.52%  sigs.k8s.io/kustomize/api/internal/builtins.applyOrdering
        0.87s  1.92%  7.36%     16.55s 36.45%  sigs.k8s.io/kustomize/kyaml/yaml.visitMappingNodeFields
        2.51s  5.53% 12.88%     15.68s 34.53%  sigs.k8s.io/kustomize/kyaml/yaml.visitFieldsWhileTrue

after

    (pprof) top20 -cum
    Showing nodes accounting for 1.23s, 3.85% of 31.98s total
    Dropped 584 nodes (cum <= 0.16s)
    Showing top 20 nodes out of 184
        flat  flat%   sum%        cum   cum%
            0     0%     0%     27.41s 85.71%  github.com/spf13/cobra.(*Command).Execute
            0     0%     0%     27.41s 85.71%  github.com/spf13/cobra.(*Command).ExecuteC
            0     0%     0%     27.41s 85.71%  github.com/spf13/cobra.(*Command).execute
            0     0%     0%     27.41s 85.71%  main.main
            0     0%     0%     27.41s 85.71%  runtime.main
            0     0%     0%     27.41s 85.71%  sigs.k8s.io/kustomize/kustomize/v5/commands/build.NewCmdBuild.func1
            0     0%     0%     26.85s 83.96%  sigs.k8s.io/kustomize/api/krusty.(*Kustomizer).Run
            0     0%     0%     22.07s 69.01%  sigs.k8s.io/kustomize/api/internal/target.(*KustTarget).MakeCustomizedResMap (inline)
            0     0%     0%     22.07s 69.01%  sigs.k8s.io/kustomize/api/internal/target.(*KustTarget).makeCustomizedResMap
        0.38s  1.19%  1.19%     20.69s 64.70%  sigs.k8s.io/kustomize/api/resource.(*Resource).CurId
            0     0%  1.19%     13.64s 42.65%  sigs.k8s.io/kustomize/api/resmap.(*resWrangler).Append
            0     0%  1.19%     13.55s 42.37%  sigs.k8s.io/kustomize/api/resmap.(*resWrangler).GetMatchingResourcesByCurrentId (inline)
        0.12s  0.38%  1.56%     13.55s 42.37%  sigs.k8s.io/kustomize/api/resmap.(*resWrangler).filteredById
        0.01s 0.031%  1.59%     12.67s 39.62%  sigs.k8s.io/kustomize/api/resmap.GetCurrentId
        0.21s  0.66%  2.25%     12.49s 39.06%  sigs.k8s.io/kustomize/api/resource.(*Resource).GetGvk (inline)
        0.51s  1.59%  3.85%     12.28s 38.40%  sigs.k8s.io/kustomize/kyaml/resid.GvkFromNode
            0     0%  3.85%     11.52s 36.02%  sigs.k8s.io/kustomize/api/internal/target.(*KustTarget).IgnoreLocal
            0     0%  3.85%     10.53s 32.93%  sigs.k8s.io/kustomize/api/internal/target.(*KustTarget).AccumulateTarget
            0     0%  3.85%     10.53s 32.93%  sigs.k8s.io/kustomize/api/internal/target.(*KustTarget).accumulateResources
            0     0%  3.85%     10.53s 32.93%  sigs.k8s.io/kustomize/api/internal/target.(*KustTarget).accumulateTarget

api/internal/builtins/SortOrderTransformer.go

@@ -74,34 +74,16 @@ func (p *SortOrderTransformerPlugin) Transform(m resmap.ResMap) (err error) {
 
 	// Sort
 	if p.SortOptions.Order == types.LegacySortOrder {
-		s := newLegacyIDSorter(m.AllIds(), p.SortOptions.LegacySortOptions)
+		s := newLegacyIDSorter(m.Resources(), p.SortOptions.LegacySortOptions)
 		sort.Sort(s)
-		err = applyOrdering(m, s.resids)
-		if err != nil {
-			return err
-		}
-	}
-	return nil
-}
 
-// applyOrdering takes resources (given in ResMap) and a desired ordering given
+		// Clear the map and re-add the resources in the sorted order.
-// as a sequence of ResIds, and updates the ResMap's resources to match the
+		m.Clear()
-// ordering.
+		for _, r := range s.resources {
-func applyOrdering(m resmap.ResMap, ordering []resid.ResId) error {
+			err := m.Append(r)
-	var err error
+			if err != nil {
-	resources := make([]*resource.Resource, m.Size())
+				return errors.WrapPrefixf(err, "SortOrderTransformer: Failed to append to resources")
-	// Clear and refill with the correct order
+			}
-	for i, id := range ordering {
-		resources[i], err = m.GetByCurrentId(id)
-		if err != nil {
-			return errors.WrapPrefixf(err, "expected match for sorting")
-		}
-	}
-	m.Clear()
-	for _, r := range resources {
-		err = m.Append(r)
-		if err != nil {
-			return errors.WrapPrefixf(err, "SortOrderTransformer: Failed to append to resources")
 		}
 	}
 	return nil
@@ -117,12 +99,17 @@ func applyOrdering(m resmap.ResMap, ordering []resid.ResId) error {
 type legacyIDSorter struct {
 	// resids only stores the metadata of the object. This is an optimization as
 	// it's expensive to compute these again and again during ordering.
-	resids     []resid.ResId
+	resids []resid.ResId
+	// Initially, we sorted the metadata (ResId) of each object and then called GetByCurrentId on each to construct the final list.
+	// The problem is that GetByCurrentId is inefficient and does a linear scan in a list every time we do that.
+	// So instead, we sort resources alongside the ResIds.
+	resources []*resource.Resource
+
 	typeOrders map[string]int
 }
 
 func newLegacyIDSorter(
-	resids []resid.ResId,
+	resources []*resource.Resource,
 	options *types.LegacySortOptions) *legacyIDSorter {
 	// Precalculate a resource ranking based on the priority lists.
 	var typeOrders = func() map[string]int {
@@ -135,10 +122,13 @@ func newLegacyIDSorter(
 		}
 		return m
 	}()
-	return &legacyIDSorter{
+
-		resids:     resids,
+	ret := &legacyIDSorter{typeOrders: typeOrders}
-		typeOrders: typeOrders,
+	for _, res := range resources {
+		ret.resids = append(ret.resids, res.CurId())
+		ret.resources = append(ret.resources, res)
 	}
+	return ret
 }
 
 var _ sort.Interface = legacyIDSorter{}
@@ -146,6 +136,7 @@ var _ sort.Interface = legacyIDSorter{}
 func (a legacyIDSorter) Len() int { return len(a.resids) }
 func (a legacyIDSorter) Swap(i, j int) {
 	a.resids[i], a.resids[j] = a.resids[j], a.resids[i]
+	a.resources[i], a.resources[j] = a.resources[j], a.resources[i]
 }
 func (a legacyIDSorter) Less(i, j int) bool {
 	if !a.resids[i].Gvk.Equals(a.resids[j].Gvk) {

plugin/builtin/sortordertransformer/SortOrderTransformer.go

@@ -77,34 +77,16 @@ func (p *plugin) Transform(m resmap.ResMap) (err error) {
 
 	// Sort
 	if p.SortOptions.Order == types.LegacySortOrder {
-		s := newLegacyIDSorter(m.AllIds(), p.SortOptions.LegacySortOptions)
+		s := newLegacyIDSorter(m.Resources(), p.SortOptions.LegacySortOptions)
 		sort.Sort(s)
-		err = applyOrdering(m, s.resids)
-		if err != nil {
-			return err
-		}
-	}
-	return nil
-}
 
-// applyOrdering takes resources (given in ResMap) and a desired ordering given
+		// Clear the map and re-add the resources in the sorted order.
-// as a sequence of ResIds, and updates the ResMap's resources to match the
+		m.Clear()
-// ordering.
+		for _, r := range s.resources {
-func applyOrdering(m resmap.ResMap, ordering []resid.ResId) error {
+			err := m.Append(r)
-	var err error
+			if err != nil {
-	resources := make([]*resource.Resource, m.Size())
+				return errors.WrapPrefixf(err, "SortOrderTransformer: Failed to append to resources")
-	// Clear and refill with the correct order
+			}
-	for i, id := range ordering {
-		resources[i], err = m.GetByCurrentId(id)
-		if err != nil {
-			return errors.WrapPrefixf(err, "expected match for sorting")
-		}
-	}
-	m.Clear()
-	for _, r := range resources {
-		err = m.Append(r)
-		if err != nil {
-			return errors.WrapPrefixf(err, "SortOrderTransformer: Failed to append to resources")
 		}
 	}
 	return nil
@@ -120,12 +102,17 @@ func applyOrdering(m resmap.ResMap, ordering []resid.ResId) error {
 type legacyIDSorter struct {
 	// resids only stores the metadata of the object. This is an optimization as
 	// it's expensive to compute these again and again during ordering.
-	resids     []resid.ResId
+	resids []resid.ResId
+	// Initially, we sorted the metadata (ResId) of each object and then called GetByCurrentId on each to construct the final list.
+	// The problem is that GetByCurrentId is inefficient and does a linear scan in a list every time we do that.
+	// So instead, we sort resources alongside the ResIds.
+	resources []*resource.Resource
+
 	typeOrders map[string]int
 }
 
 func newLegacyIDSorter(
-	resids []resid.ResId,
+	resources []*resource.Resource,
 	options *types.LegacySortOptions) *legacyIDSorter {
 	// Precalculate a resource ranking based on the priority lists.
 	var typeOrders = func() map[string]int {
@@ -138,10 +125,13 @@ func newLegacyIDSorter(
 		}
 		return m
 	}()
-	return &legacyIDSorter{
+
-		resids:     resids,
+	ret := &legacyIDSorter{typeOrders: typeOrders}
-		typeOrders: typeOrders,
+	for _, res := range resources {
+		ret.resids = append(ret.resids, res.CurId())
+		ret.resources = append(ret.resources, res)
 	}
+	return ret
 }
 
 var _ sort.Interface = legacyIDSorter{}
@@ -149,6 +139,7 @@ var _ sort.Interface = legacyIDSorter{}
 func (a legacyIDSorter) Len() int { return len(a.resids) }
 func (a legacyIDSorter) Swap(i, j int) {
 	a.resids[i], a.resids[j] = a.resids[j], a.resids[i]
+	a.resources[i], a.resources[j] = a.resources[j], a.resources[i]
 }
 func (a legacyIDSorter) Less(i, j int) bool {
 	if !a.resids[i].Gvk.Equals(a.resids[j].Gvk) {