Adds performance PR template

Encourages optimization proposals to document baselines, benchmark evidence, trade-offs, and verification steps for reproducible reviews.

Author: LoserCheems

.github/PULL_REQUEST_TEMPLATE/performance_optimization.md

@@ -0,0 +1,31 @@
+---
+name: "Performance Optimization"
+about: "Optimize performance with benchmark evidence"
+title: "[PERFORMANCE OPTIMIZATION] "
+labels: ["performance"]
+
+---
+
+## Summary
+- What is optimized and why?
+
+## Baseline metrics
+- Provide the current performance numbers and environment.
+
+## Approach
+- Describe the optimization techniques used.
+
+## Results
+- Share before/after benchmarks and how to reproduce them.
+
+## Impact
+- Note memory, throughput trade-offs, or hardware-specific considerations.
+
+## Risks
+- Highlight edge cases, correctness risks, or gating tests added.
+
+## Checklist
+- [ ] Linked issue provided
+- [ ] Benchmarks included and reproducible
+- [ ] No accuracy regression
+- [ ] Docs updated where needed