performance

I have a slow PostgreSQL query and I ran EXPLAIN ANALYZE. I need to understand how to read the output, identify why the query is slow (wrong index, bad join order, row estimate mismatch), and know wha...

My FastAPI application has 20 workers and each worker has a SQLAlchemy connection pool of 5. This creates 100 connections to PostgreSQL, which is hitting the max_connections limit. I need connection p...

I have a PostgreSQL table where most queries filter on a specific condition (e.g., status='validated'). Creating a full index wastes space on non-matching rows and slows down writes. I want to create ...

My React app re-renders excessively. I want practical guidance on when useMemo and useCallback actually help vs when they are premature optimization that adds overhead without benefit.

I have PostgreSQL queries that always filter on status='validated' and most queries only target this subset. A full index wastes space indexing pending rows I never query. I want partial indexes for f...

My React app has a large JavaScript bundle. I want to split the code so users only download JS for the current page using React.lazy for component-level code splitting.

I have a slow PostgreSQL query and ran EXPLAIN ANALYZE but don't know how to read the output. I need to identify why the query is slow (wrong index, bad join order, row estimate mismatch) and know wha...

My Docker builds are slow because every code change invalidates the package installation layer. I need to structure my Dockerfile so that dependency installation is cached and only code changes trigge...

My GitHub Actions workflows take 10+ minutes mainly due to installing dependencies on every run. I need to cache dependencies, understand what to cache for Python and Node.js, and handle cache invalid...

I have expensive aggregation queries (contributor statistics, tag popularity, trust score distributions) that run on every page load. I want to precompute these and refresh them periodically.

Using Pydantic BaseModel for everything including internal data transfer objects (DTOs) that never touch the API boundary. Pydantic validation overhead is unnecessary for internal models. Need guidanc...

SQLAlchemy ORM queries are unexpectedly slow. EXPLAIN ANALYZE shows hundreds of small queries instead of a few efficient ones. The N+1 problem: loading a list of traces then accessing trace.tags trigg...

Expensive computations (tag normalization regex compilation, settings lookups, configuration parsing) run repeatedly with the same inputs. Need simple memoization without external caching infrastructu...

Queries filter on multiple columns: `WHERE status = 'validated' AND trust_score > 0.5 ORDER BY created_at DESC`. Single-column indexes on each column aren't used effectively. Query planner does a full...

Query is slow but unsure why. Running EXPLAIN ANALYZE produces verbose output with nodes like 'Seq Scan', 'Hash Join', 'Bitmap Heap Scan' and numbers for cost, rows, and buffers. Need to understand wh...

Inserting thousands of rows one at a time with individual session.add() calls is too slow. Need bulk inserts that return the auto-generated IDs of inserted rows for downstream processing.

Bundle size is large because all components load upfront. Some pages are rarely visited. Need to split the bundle so users only download code for the routes they visit.

Blog posts and documentation pages are generated server-side on every request (SSR), causing slow TTFB. Content changes infrequently. Need static generation benefits (CDN caching, fast delivery) with ...

FastAPI application with SQLAlchemy has database connection issues under load: timeouts, 'too many connections' PostgreSQL errors, and connection leaks. Default connection pool settings are not tuned ...