do not calculate total directory size unless it will be displayed

src/core.rs

@@ -124,7 +124,8 @@ impl Core {
                 meta_list.push(meta);
             };
         }
-        if self.flags.total_size.0 {
+        // Only calculate the total size of a directory if it will be displayed
+        if self.flags.total_size.0 && self.flags.blocks.displays_size() {
             for meta in &mut meta_list.iter_mut() {
                 meta.calculate_total_size();
             }

src/flags/blocks.rs

@@ -151,6 +151,10 @@ impl Blocks {
         }
     }
 
+    pub fn displays_size(&self) -> bool {
+        self.0.contains(&Block::Size)
+    }
+
     /// Tnserts a [Block] of variant [INode](Block::Context), if `self` does not already contain a
     /// [Block] of that variant. The positioning will be best-effort approximation of coreutils
     /// ls position for a security context