diff --git a/internal/handler/dashboard.go b/internal/handler/dashboard.go
index a47e7db..f38cdd8 100644
--- a/internal/handler/dashboard.go
+++ b/internal/handler/dashboard.go
@@ -79,8 +79,8 @@ func (handler DashboardImpl) handleDashboardMainChart() http.HandlerFunc {
 		savingsBuilder := strings.Builder{}
 
 		for _, entry := range series {
-			accountBuilder.WriteString(fmt.Sprintf(`["%s",%.2f],`, entry.Day.Format(time.RFC3339), float64(entry.Value)/100))
-			savingsBuilder.WriteString(fmt.Sprintf(`["%s",%.2f],`, entry.Day.Format(time.RFC3339), float64(entry.Savings)/100))
+			fmt.Fprintf(&accountBuilder, `["%s",%.2f],`, entry.Day.Format(time.RFC3339), float64(entry.Value)/100)
+			fmt.Fprintf(&savingsBuilder, `["%s",%.2f],`, entry.Day.Format(time.RFC3339), float64(entry.Savings)/100)
 		}
 
 		account := accountBuilder.String()
@@ -148,15 +148,15 @@ func (handler DashboardImpl) handleDashboardTreasureChests() http.HandlerFunc {
 
 			for _, child := range item.Children {
 				if child.Value < 0 {
-					childrenBuilder.WriteString(fmt.Sprintf(`{"name":"%s\n%.2f €","value":%d},`, child.Name, float64(child.Value)/100, -child.Value))
+					fmt.Fprintf(&childrenBuilder, `{"name":"%s\n%.2f €","value":%d},`, child.Name, float64(child.Value)/100, -child.Value)
 				} else {
-					childrenBuilder.WriteString(fmt.Sprintf(`{"name":"%s\n%.2f €","value":%d},`, child.Name, float64(child.Value)/100, child.Value))
+					fmt.Fprintf(&childrenBuilder, `{"name":"%s\n%.2f €","value":%d},`, child.Name, float64(child.Value)/100, child.Value)
 				}
 			}
 
 			children := childrenBuilder.String()
 			children = children[:len(children)-1]
-			dataBuilder.WriteString(fmt.Sprintf(`{"name":"%s","children":[%s]},`, item.Name, children))
+			fmt.Fprintf(&dataBuilder, `{"name":"%s","children":[%s]},`, item.Name, children)
 		}
 		data := dataBuilder.String()
 		data = data[:len(data)-1]
@@ -212,7 +212,7 @@ func (handler DashboardImpl) handleDashboardTreasureChest() http.HandlerFunc {
 		valueBuilder := strings.Builder{}
 
 		for _, entry := range series {
-			valueBuilder.WriteString(fmt.Sprintf(`["%s",%.2f],`, entry.Day.Format(time.RFC3339), float64(entry.Value)/100))
+			fmt.Fprintf(&valueBuilder, `["%s",%.2f],`, entry.Day.Format(time.RFC3339), float64(entry.Value)/100)
 		}
 
 		value := valueBuilder.String()