diff --git a/show.go b/show.go
index 39f197c1..32e4f08f 100644
--- a/show.go
+++ b/show.go
@@ -7,6 +7,7 @@ import (
 	"os"
 	"sort"
 	"strings"
+	"sync"
 	"text/template"
 
 	"github.com/nokia/ntt/internal/env"
@@ -77,36 +78,48 @@ func printJSON(report *ConfigReport, keys []string) error {
 	}
 
 	if !dumb {
-		var list []project.TestConfig
+		mu := sync.Mutex{}
+		wg := sync.WaitGroup{}
+		wg.Add(len(files))
+		glist := make([]project.TestConfig, 0, len(files))
 		for _, file := range files {
-			tree := ttcn3.ParseFile(file)
-			if tree.Err != nil {
-				report.err = errors.Join(report.err, tree.Err)
-			}
-			tree.Inspect(func(n syntax.Node) bool {
-				switch n := n.(type) {
-				case *syntax.FuncDecl:
-					if n.IsTest() || n.IsControl() {
+			go func() {
+				defer wg.Done()
+
+				tree := ttcn3.ParseFile(file)
+				if tree.Err != nil {
+					report.err = errors.Join(report.err, tree.Err)
+				}
+				list := make([]project.TestConfig, 0, len(tree.Names))
+				tree.Inspect(func(n syntax.Node) bool {
+					switch n := n.(type) {
+					case *syntax.FuncDecl:
+						if n.IsTest() || n.IsControl() {
+							break
+						}
+						return false
+					case *syntax.ControlPart:
 						break
+					default:
+						return true
+					}
+					name := tree.QualifiedName(n)
+					tc, err := report.TestConfigs(name, presets...)
+					if err != nil {
+						log.Debugf("implementation error: %s\n", err)
+					}
+					if len(tc) > 0 {
+						list = append(list, tc...)
 					}
 					return false
-				case *syntax.ControlPart:
-					break
-				default:
-					return true
-				}
-				name := tree.QualifiedName(n)
-				tc, err := report.TestConfigs(name, presets...)
-				if err != nil {
-					log.Debugf("implementation error: %s\n", err)
-				}
-				if len(tc) > 0 {
-					list = append(list, tc...)
-				}
-				return false
-			})
+				})
+				mu.Lock()
+				glist = append(glist, list...)
+				mu.Unlock()
+			}()
 		}
-		report.Execute = list
+		wg.Wait()
+		report.Execute = glist
 	}
 
 	b, err := yaml.MarshalJSON(report)