优化：拖拽视图性能优化，拖拽期间禁止重绘canvas

src/utils/perfMonitor.ts

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+/**
+ * 性能监控工具
+ */
+
+let lastLogTime = 0
+const LOG_THROTTLE = 100 // 最多每 100ms 输出一次日志
+
+export const perfMonitor = {
+  /**
+   * 记录性能日志（自动节流）
+   */
+  log(tag: string, data: unknown) {
+    const now = Date.now()
+    if (now - lastLogTime < LOG_THROTTLE) {
+      return
+    }
+    lastLogTime = now
+
+    // eslint-disable-next-line no-console
+    console.log(`[Perf] ${tag}:`, data)
+  },
+
+  /**
+   * 测量函数执行时间
+   */
+  measure<T>(tag: string, fn: () => T): T {
+    const start = performance.now()
+    const result = fn()
+    const end = performance.now()
+    const duration = end - start
+
+    if (duration > 5) {
+      // 只记录耗时超过 5ms 的操作
+      // eslint-disable-next-line no-console
+      console.log(`[Perf] ${tag}: ${duration.toFixed(2)}ms`)
+    }
+
+    return result
+  },
+}