Feature Request

Summary

One of the main benefits of moving to FastAPI is being able to handle I/O-bound work asynchronously so slow requests do not block workers and degrade performance for unrelated traffic.

We currently have several partial endpoints with relatively high response times. Endpoints that spend time waiting on outbound HTTP requests should be good candidates to convert to async. Endpoints that are tightly coupled to synchronous database access may be harder to improve and may need separate investigation.

Current timings:

Problem

These endpoints may be tying up workers while waiting on network-bound operations. In a FastAPI app, this reduces the benefit of the migration and can slow down other requests under load.

Goal

Convert the partial endpoints below to async where feasible, prioritizing endpoints that perform outbound HTTP calls.

Scope

Endpoints to evaluate and convert:

• 🟢 /partials/AffiliateLinks.json
  • Should be pretty doable, making the external calls async. But still some work. Note, we'll probably skip the amazon APIs until Amazon Product Advertising API deprecated April 30, 2026 #12255 is sorted out.
  • Part 1: Refactor AffiliateLinks to Remove Template-Side Network Requests #12271
  • Part 2: make betterworldbooks async #12404
• 🟢 /partials/BPListsSection.json #12270
• CarouselLoadMore partial fully async
  • _do_search_query make _do_search_query async for CarouselLoadMore in fastapi #12482
  • _do_browse_query make _do_browse_query async #12484
  • _do_trends_query asyncify code for trending and availability fastapi #12508
  • _do_subjects_query make _do_subjects_query async #12495
• 🟢 /partials/FulltextSearchSuggestion.js #12257
• /partials/LazyCarousel.json
  • 🟡 /partials/LazyCarousel.json #12288
  • Requires a medium size template refactoring so that we can pull the query logic into async land
• 🔴 /partials/MyBooksDropperLists.json
  • Requires async infobase client
• 🔴 /partials/ReadingGoalProgress.json
  • This basically just does a DB call so we are not gonna make this change.
• 🟢 /partials/SearchFacets.json #12256

Notes

• Endpoints that make outbound HTTP requests should be straightforward candidates for async conversion.
• Endpoints that directly depend on synchronous database access may not benefit immediately, or may require additional refactoring.
• This work can be done in one PR or split into multiple PRs, depending on complexity and risk.
• Please see make CarouselLoadMore partial fully async #12252 as an example for the pattern we want to follow.

I will be working on this as it is somewhat time sensitive for performance.

Breakdown