diff --git a/orga/performance-trackings.md b/orga/performance-trackings.md
index d599dd25615..05a75d7d2f0 100644
--- a/orga/performance-trackings.md
+++ b/orga/performance-trackings.md
@@ -1338,3 +1338,19 @@ compareCounts: 1431962
 AFTER (using custom low index):
 time for "merge sorted arrays": 847.3687120079994ms
 compareCounts: 1261729
+
+
+## Improve getIndexableStringMonad()()
+
+BEFORE:
+91.24348497390747
+86.09021002054214
+89.61336600780487
+87.5959959924221
+87.1041649878025
+
+
+AFTER (fix getNumberIndexString()):
+76.63579297065735
+63.062547981739044
+80.47493699193001
diff --git a/src/custom-index.ts b/src/custom-index.ts
index aacfc529c46..0cb683ea36d 100644
--- a/src/custom-index.ts
+++ b/src/custom-index.ts
@@ -206,14 +206,12 @@ export function getNumberIndexString(
         fieldValue = parsedLengths.maximum;
     }
 
-    let str: string = '';
     const nonDecimalsValueAsString = (Math.floor(fieldValue) - parsedLengths.roundedMinimum).toString();
-    str += nonDecimalsValueAsString.padStart(parsedLengths.nonDecimals, '0');
-
-    const splitByDecimalPoint = fieldValue.toString().split('.');
-    const decimalValueAsString = splitByDecimalPoint.length > 1 ? splitByDecimalPoint[1] : '0';
+    let str = nonDecimalsValueAsString.padStart(parsedLengths.nonDecimals, '0');
 
     if (parsedLengths.decimals > 0) {
+        const splitByDecimalPoint = fieldValue.toString().split('.');
+        const decimalValueAsString = splitByDecimalPoint.length > 1 ? splitByDecimalPoint[1] : '0';
         str += decimalValueAsString.padEnd(parsedLengths.decimals, '0');
     }
     return str;