Performance Analysis: Document codebase performance issues with prioritized recommendations

[Copilot]

Technical Summary

Comprehensive analysis of the Connect-ID codebase identifying 14 performance issues, organized by priority with actionable fixes.

High Priority (5 issues):

• N+1 queries in send_bulk_notification(), RetrieveMessageView, RetrieveNotificationView
• Sequential external API calls in resend_notifications_for_undelivered_messages()
• Synchronous blocking calls (Twilio, OpenChatStudio, Connect API) in request handlers

Medium Priority (5 issues):

• Missing DB indexes on ConnectUser.phone_number+is_active, Message.received+direction, Notification.received
• Loop with individual DB ops in AddCredential
• Synchronous geocoding and S3 operations in request path

Low Priority (4 issues):

• Client instantiation per request (Twilio, S3)
• Python sorting instead of DB-level ORDER BY
• O(n²) sorting algorithm in notification response

Example N+1 pattern identified:

# Current: N+1 queries
for user in users:
    fcm_device = FCMDevice.objects.filter(user=user, active=True).first()  # Query per user

# Recommended: Single prefetch
users = ConnectUser.objects.filter(...).prefetch_related(
    Prefetch('fcmdevice_set', queryset=FCMDevice.objects.filter(active=True), to_attr='active_devices')
)

Added PERFORMANCE.md with detailed analysis, code samples, and priority matrix.

Logging and monitoring

N/A - documentation only.

Safety Assurance

Safety story

• Documentation-only change; no code modifications

• All 207 existing tests pass

• I am confident that this change will not break current and/or previous versions of CommCare apps

Automated test coverage

N/A - no code changes.

QA Plan

N/A - documentation only.

Labels & Review

• The set of people pinged as reviewers is appropriate for the level of risk of the change

Warning

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Original prompt

---

This section details on the original issue you should resolve

<issue_title>Investigate performance of code in codebase</issue_title>
<issue_description>Look over the whole codebase and compile a list of performance issues that we need to address. Triage the list and provide clear actionable steps.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Investigate performance of code in codebase #210

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[sravfeyn]

The number of channels is not much so this is probably not that important

[sravfeyn]

This is suggesting a change in feature behaviour, so can't implement this

[sravfeyn]

Added in #215

[sravfeyn]

Added in #215