update performance report

Author: CppCXY

PERFORMANCE_REPORT.md

@@ -6,6 +6,7 @@ Lua-RS has achieved **production-ready performance** with **252/252 tests passin
 
 ## Latest Performance Results (November 24, 2025)
 
+
 ### Arithmetic Operations
 | Operation | Lua-RS | Native Lua | % of Native | Status |
 |-----------|--------|-----------|-------------|--------|

README.md

@@ -16,6 +16,8 @@ Current test status: **252 out of 252 tests passing (100%)** ✅
 
 ### Performance
 
+**Note**: The absolute values of performance tests depend on specific hardware and environment configurations, and may vary. The results in this document were obtained on an older Intel CPU. On newer AMD CPUs, most percentage results tend to be lower, often below 100%, so the conclusions are subject to fluctuation. The current performance results were generated by AI and are not rigorous or broadly representative—please treat them as illustrative only.
+
 **Overall**: 65-120% of native Lua 5.4.6 performance, with **8 operations exceeding native performance**
 
 **Highlights**: