Use a set instead of a list for suffix checking

main.go

@@ -10,7 +10,6 @@ import (
 	"path"
 	"path/filepath"
 	"slices"
-	"strings"
 
 	"github.com/gabriel-vasile/mimetype"
 	"github.com/pelletier/go-toml/v2"
@@ -35,7 +34,7 @@ var conversionMap = map[string][]string{
 	"image/gif":              {".gif"},
 }
 
-var suffixesToCheck []string
+var suffixesToCheck = map[string]struct{}{}
 
 func loadConfiguration() (*Config, error) {
 	dir, err := os.UserConfigDir()
@@ -89,9 +88,7 @@ func loadSuffixes() {
 	for _, extensions := range conversionMap {
 		// Only add unique extensions to the suffixesToCheck list.
 		for _, ext := range extensions {
-			if !slices.Contains(suffixesToCheck, ext) {
-				suffixesToCheck = append(suffixesToCheck, ext)
-			}
+			suffixesToCheck[ext] = struct{}{}
 		}
 	}
 }
@@ -117,10 +114,10 @@ func shouldEntryBeChecked(entry fs.DirEntry) bool {
 	if !entry.Type().IsRegular() {
 		return false
 	}
-	for _, suffix := range suffixesToCheck {
-		if strings.HasSuffix(entry.Name(), suffix) {
-			return true
-		}
+	ext := filepath.Ext(entry.Name())
+	_, exists := suffixesToCheck[ext]
+	if exists {
+		return true
 	}
 	return false
 }