--- title: "App got slow once real users arrived" description: "Vibe coded apps slow down at real data sizes because of missing indexes and per-row policies. How to find and fix them in Supabase." url: https://whocanfixmyapp.com/problems/app-got-slow-once-real-users-arrived --- [Home](https://whocanfixmyapp.com/) / [Problems](https://whocanfixmyapp.com/problems) / [Data and database](https://whocanfixmyapp.com/problems#data-and-database) # App got slow once real users arrived VC-43 · Supabase · Next.js · Updated October 2026 · By [Nathaniel Kelley](https://whocanfixmyapp.com/authors/nathaniel-kelley) Quick verdict Partly fixable yourself. An index is one line, finding the right one needs care - **How serious**: Medium - **Fix it yourself?**: Partly, some steps need a developer - **Typical cost**: $49–$800 one-off check, or €99–$990 for a single fix ([prices](https://whocanfixmyapp.com/pricing)) - **Top rated for Supabase**: [Redlab](https://whocanfixmyapp.com/companies/redlab) · **10.0**/10 **What you see.** Pages that opened instantly with test data now take seconds, and Supabase shows slow queries or CPU warnings. ## Why it happens AI-built apps are tested on 50 rows and launched on 50,000. Without an index, Postgres scans every row in a table to find a match, so a lookup that was instant grows with your data. Supabase describes an index as a lookup list that finds rows without scanning the whole table. Row Level Security makes this worse. Every policy runs on every row a query touches, and Supabase notes that an unindexed filter column turns a read into a sequential scan. Policies that call `auth.uid()` directly, instead of `(select auth.uid())`, run that function once per row. Add the usual builder habits, such as loading every row instead of a page, fetching related records one by one, and full-size images, and the app feels broken under modest traffic. The good news is that the Supabase Performance Advisor and Index Advisor point at most of this automatically. ## Fix it yourself 1. In the Supabase dashboard open the **Performance Advisor**. Look for `unindexed_foreign_keys` and `auth_rls_initplan` findings. 2. Open **Query Performance**, click the slowest query, choose the **Indexes** tab and enable the Index Advisor. It proposes indexes for that query. 3. Create the index in the SQL editor, for example `create index concurrently idx_orders_user_id on orders (user_id)`. Index columns you filter, join or sort on, and columns your policies use. 4. Ask your builder to rewrite policies as `(select auth.uid()) = user_id` so the user lookup runs once per query, not once per row. 5. Load 20 to 50 rows per page instead of everything, and resize images before upload. See [the checklist](https://whocanfixmyapp.com/checklist) items COST-03 and COST-04. 6. Re-check the query plan. Supabase advises removing an index that did not reduce the query's cost, because every index slows writes. ## When to get an engineer Hire an engineer when the advisor lists dozens of findings, when the slow part is a server function or an AI call rather than the database, or when adding indexes did not help. Share the Query Performance report, the slow pages, and your user count. A one-off check costs $49–$800 and usually lands the top five fixes. A single fix, such as indexing and rewriting policies for one feature, runs €99–$990 over about two days. ## Top-rated companies for Supabase apps Ranked by our score: published prices, scope of work, AI tools named, timing and a low-risk first step. [How we score](https://whocanfixmyapp.com/methodology#score). - 1 · [Redlab](https://whocanfixmyapp.com/companies/redlab) · **10.0**/10 · Best for: A full rescue by one team that keeps building · Free first step · from $490 - 2 · [Vibe Code Rescue (Lev Arakelyan)](https://whocanfixmyapp.com/companies/vibe-code-rescue-lev-arakelyan) · **9.0**/10 · Best for: A one-off check and a cleanup · From $299 - 3 · [LazyCodeLab](https://whocanfixmyapp.com/companies/lazycodelab) · **9.0**/10 · Best for: A one-off check and a cleanup · From $399 [All 29 Supabase companies, ranked](https://whocanfixmyapp.com/best/supabase-developers) ## Check these COST-02 · Medium Database columns you filter on are indexed Queries that scan whole tables are fast at 100 rows and slow at 100,000. COST-03 · Medium Key pages load fast on a phone Run PageSpeed Insights on the home page and the main app screen, on mobile. COST-04 · Medium Images are resized and compressed Uploaded photos served at full size are a common cause of slow pages. DATA-01 · Critical Access rules are on for every table In Supabase, open Table Editor: every table should show RLS enabled, with at least one policy. In Firebase, your rules should never say `allow read, write: if true`. ## Questions ### Should I just pay for bigger Supabase compute? Try indexes and policy fixes first. They are one-line changes and remove the scans that waste the compute you already have. ### Can too many indexes hurt? Yes. Supabase notes that indexes add write overhead and storage, so index the columns you filter and join on, not every column. Sources: [Supabase docs: Managing Indexes in Postgres](https://supabase.com/docs/guides/database/postgres/indexes); [Supabase docs: Query Optimization](https://supabase.com/docs/guides/database/query-optimization); [Supabase docs: Row Level Security](https://supabase.com/docs/guides/database/postgres/row-level-security); [Supabase docs: Performance and Security Advisors](https://supabase.com/docs/guides/database/database-advisors). **Supabase guide** What Supabase builds, where it breaks and how to check it: [Supabase RLS audit: how to check an AI-built app's database rules](https://whocanfixmyapp.com/guides/supabase). **Same category** - [My Supabase service_role key is in the browser](https://whocanfixmyapp.com/problems/supabase-secret-key-in-the-browser) - [Data saves with no error but never shows up](https://whocanfixmyapp.com/problems/data-saves-with-no-error-but-never-shows-up) - [Supabase project paused or free tier limit reached](https://whocanfixmyapp.com/problems/supabase-project-paused-or-free-tier-limit) - [I have no backups and don't know how to restore](https://whocanfixmyapp.com/problems/no-backups-and-i-dont-know-how-to-restore) - [Test data and real customer data are in one database](https://whocanfixmyapp.com/problems/test-data-mixed-with-real-customer-data) - [Firebase rules are set to allow read, write: true](https://whocanfixmyapp.com/problems/firebase-rules-allow-read-write-true) [All data and database problems](https://whocanfixmyapp.com/problems#data-and-database) **Run every check** The [production checklist](https://whocanfixmyapp.com/checklist) has all 24 checks with a verdict.