perf(minifier): avoid unecessary import/export merging for cjs/scripts (#27291)

- disable processing of import/export for files that can't contain it
- if `target_specifiers` are fully consumed we do not have to attempt to drop them

crates/oxc_minifier/src/peephole/minimize_statements.rs

@@ -230,10 +230,6 @@ impl<'a> PeepholeOptimizations {
                 continue;
             };
 
-            {
-                let source_stmt = stmts.get(statement_index).unwrap();
-                ctx.drop_statement(source_stmt);
-            }
             let Statement::ImportDeclaration(source_import) =
                 stmts.get_mut(statement_index).unwrap()
             else {
@@ -272,7 +268,8 @@ impl<'a> PeepholeOptimizations {
         // Remove imports in reverse order so removing a later import does not
         // shift the indices of any merge that is still waiting to be applied.
         for &source_index in merges.iter().rev() {
-            stmts.remove(source_index);
+            let source_stmt = stmts.remove(source_index);
+            ctx.drop_statement(&source_stmt);
         }
     }
 

crates/oxc_minifier/src/peephole/mod.rs

@@ -390,8 +390,11 @@ impl<'a> Traverse<'a> for PeepholeOptimizations {
     }
 
     fn exit_program(&mut self, program: &mut Program<'a>, ctx: &mut TraverseCtx<'a>) {
-        Self::merge_imports(&mut program.body, ctx);
-        Self::merge_import_export(&mut program.body, ctx);
+        // skip merging import / export for cjs and scripts as they can't contain import stmt
+        if !ctx.source_type().is_script() && !ctx.source_type().is_commonjs() {
+            Self::merge_imports(&mut program.body, ctx);
+            Self::merge_import_export(&mut program.body, ctx);
+        }
         // Private member usage is collected only in full optimization mode.
         debug_assert!(ctx.is_tree_shake_only() || ctx.state.private_member_usage.is_at_root());
     }