[PERF] Cache leaderboard API response for 5 minutes to reduce database load

[Priyanshu-byte-coder]

Problem

/api/leaderboard recomputes rankings from scratch on every request by aggregating metrics for all opted-in users. With hundreds of users, this triggers many DB queries and slows the page.

Proposed solution

Cache the leaderboard response for 5 minutes using Redis (Upstash) or Next.js unstable_cache:

import { unstable_cache } from 'next/cache';
const getCachedLeaderboard = unstable_cache(
  async () => computeLeaderboard(),
  ['leaderboard'],
  { revalidate: 300 }
);

Trade-offs

• Rankings may be up to 5 minutes stale — acceptable since leaderboard is not real-time
• Cache should be invalidated when a user opts out of the leaderboard

Acceptance criteria

• Leaderboard response cached for 5 minutes
• Cache invalidated on opt-out
• Response time for leaderboard < 200ms on cache hit

[shauryavardhan1307]

Hi @Priyanshu-byte-coder . I am a Gssoc contributor. Please assign this to me

[ask-z4ch]

/assign
Hi @Priyanshu-byte-coder, I would like to work on this issue under GSSoC 2026.
To resolve this, I will:

• Wrap buildLeaderboard() in unstable_cache with a 300-second revalidate so the response is served from the Next.js data cache instead of recomputing from scratch on every request
• Modify src/app/api/leaderboard/route.ts GET handler to use unstable_cache() and add cache-tag invalidation via revalidateTag("leaderboard") in src/lib/leaderboard.ts clearLeaderboardCache() so opt-outs are reflected immediately
• Ensure the code matches the project's formatting and styling rules without adding redundant imports
• Manually verify and test the updated execution path to guarantee zero regressions

I will have a clean pull request raised within 24 to 48 hours!

[github-actions]

@ask-z4ch You already have 2 open issue(s) assigned. Complete those first before picking up more.

[harshitanagpal05]

i'd like to work on this pls assign it to me under gssoc'26?

[github-actions]

Assigned to @harshitanagpal05! You have 7 days to open a PR. No PR after 7 days = auto-unassigned so others can pick it up. Good luck!

[anshul23102]

I can implement 5-minute caching for leaderboard API response to reduce database load. Will improve performance significantly.

/assign