Performance issues

Slow queries, slow page loads, slow agent responses. Diagnosis and fixes.

Common performance issues and where to fix.

Slow Convex queries

Query takes >1s

Almost always: missing index. The query is using .filter() instead of .withIndex(). Add an appropriate index to the schema; re-prompt or hand-edit the query to use it.

`.collect()` returning huge arrays

Replace with .paginate() to fetch incrementally. See Pagination.

Deep N+1 problem

Joining many related records inside a query. Either denormalize or batch the lookups.

Slow page loads

Initial load >3s

Bundle too large. Code-split routes, lazy-load heavy components, audit npm dependencies.

Time to interactive slow

Render-blocking resources or many small fetches. Use Suspense boundaries; combine queries.

Images slow

Use WebP / AVIF; serve appropriately-sized images; lazy-load below-the-fold.

Slow agent responses

Build takes >2 min

Large project (1000+ files) or expensive type-check. Sometimes unavoidable; consider modularizing.

Agent retries multiple times

Type errors require multiple corrections. Often a sign the prompt set up an inconsistent ask. Re-prompt with the resolution.

Profiling

vly’s editor includes a Convex query profiler:

vly convex query-stats --project prj_01...

Shows top slow queries, top missed-index queries, and recommendations.

For frontend perf, use Chrome DevTools → Performance tab as usual.

Related

Indexes

Make queries fast.

Pagination

Avoid loading huge arrays.

Caching

For expensive computations.