[Customer Issue] App is extremely slow during lunch hours (11am-1pm)

[dajwalia-ms]

Every day between 11am and 1pm, the Grubify app becomes very slow. Pages take 10-15 seconds to load, and sometimes I get timeout errors. The restaurant listing page is the worst — it barely loads.

Outside of these hours, the app works fine. We have about 500 concurrent users during peak lunch time. Is there a scaling issue?

[jonielsen]

Grubify SRE Agent Bot 🤖

Triage Classification

Field	Value
Category	Performance
Severity	🟡 Medium
Status	Triaged

Analysis

This issue reports severe performance degradation during peak lunch hours (11am-1pm) with ~500 concurrent users. Pages take 10-15 seconds to load, with the restaurant listing page being the worst affected. This is consistent with known performance issues reported in issues #103, #108, #113, #118, #143, #148, #153, #158, #163, #178.

Likely contributing factors:

1. Memory pressure from CartController leak — the known OOM issue in CartController.AddItemToCart causes memory pressure that degrades overall app performance, especially under load
2. Scaling configuration — Azure Container Apps may not be scaling fast enough to handle the lunch rush spike from ~50 to ~500 concurrent users
3. API latency — /api/restaurants endpoint may have inefficient queries or missing pagination
4. Frontend rendering — RestaurantPage.tsx may be re-rendering excessively with large restaurant lists

Recommended Labels

performance, severity-medium, needs-more-info, triage

Next Steps

1. Review Azure Container Apps scaling rules — ensure min/max replicas and scaling thresholds are appropriate for 500 concurrent users
2. Profile API response times for /api/restaurants during peak hours
3. Check container CPU and memory metrics during 11am-1pm window
4. Investigate whether the CartController memory leak is contributing to overall performance degradation during peak load
5. Review RestaurantPage.tsx rendering performance with React DevTools

Additional Info Needed

• Are timeout errors HTTP 408, 502, 503, or 504?
• Which specific pages are slowest (restaurant list, menu, cart, checkout)?
• Has this been getting progressively worse or started suddenly?

[seanbot2000]

🤖 Grubify SRE Agent Bot

Classification: Performance
Severity: High

Analysis: The application shows a repeatable peak-time degradation between 11:00 and 13:00, including 10-15 second page loads and timeouts at roughly 500 concurrent users. The restaurant listing is the primary affected flow, which is consistent with a capacity or scaling bottleneck.

Next steps: Review request latency, timeout rate, replica count, CPU/memory utilization, and autoscaling behavior for the lunch-hour window; load-test the restaurant listing path at comparable concurrency.

🔧 Status: Performance investigation needed

[TekExpo]

🤖 Grubify SRE Agent Bot

Classification: Performance
Severity: Medium

Analysis:
The reporter describes a repeatable peak-time performance degradation between 11am-1pm with ~500 concurrent users. Symptoms include 10-15 second page loads and timeout errors, with the restaurant listing page most affected. Outside peak hours the app works fine, pointing to a capacity/scaling bottleneck rather than a code defect.

Likely contributing factors:

• Azure Container Apps autoscaling may not be ramping fast enough for the lunch rush spike
• The known CartController memory leak compounds performance degradation under load
• The /api/restaurants endpoint may have inefficient queries or missing pagination

Recommended labels: performance, severity-medium
(Note: labels could not be applied automatically due to repository permission restrictions)

Next steps:

1. Review Container Apps scaling rules (min/max replicas, scaling thresholds) for 500 concurrent users
2. Profile API response times for /api/restaurants during the 11am-1pm window
3. Check container CPU and memory metrics during peak hours
4. Investigate whether the CartController memory leak contributes to overall degradation

Questions for reporter:

• Are the timeout errors HTTP 408, 502, 503, or 504?
• Which specific pages are slowest (restaurant list, menu, cart, checkout)?
• Has this been getting progressively worse or did it start suddenly?

🔧 Status: Performance investigation needed