Real Talk: How Supabase Actually Performs When Your App Gets Popular

Supabase is PostgreSQL with extra bells and whistles. It's not just "Firebase with SQL" - it's actually pretty clever under the hood.

The Numbers That Actually Matter - September 2025

I actually looked up their benchmarks because marketing numbers are usually bullshit. These are legit - they used k6 against real AWS instances:

• Real-time messaging: 224,000 messages/second (that's actually impressive)
• Database connections: 32,000 concurrent WebSocket connections
• Latency: 6ms median, 28ms 95th percentile
• New connections: 320/second

These numbers matter because they tell you where you'll hit walls.

PostgreSQL: The Good and The Bullshit

PostgreSQL will murder you when you need high writes: ACID compliance is great until you need 50,000 writes/sec and you're bottlenecked on WAL writer processes. I've watched apps cruise along at 10,000 reads/second then shit the bed completely on write spikes during Black Friday sales.

The full-text search and PostGIS are legitimately good though. Try doing geospatial queries in Firebase - you'll want to throw your laptop out the window. The JSON operations are also solid - better than most NoSQL databases.

PostgreSQL performance characteristics under different workloads

Real-Time: The Thing That'll Murder Your Database

Real-time subscriptions? Single-threaded nightmare. One slow query backs up everything because they process changes in order to maintain ordering.

Here's the nightmare scenario: 100 users subscribed to a table, you insert one row, boom - 100 authorization checks. RLS policies checking permissions on every row? Your 5ms queries just became 200ms disasters.

Thank god they added broadcast channels because database subscriptions are a performance disaster waiting to happen. We hit 800,000+ messages/second using broadcasts - that's 80x better than the database subscriptions.

Pro tip from the trenches: Broadcast channels saved our ass, but don't try sending binary data - it'll silently fail and you'll debug for hours wondering why your file uploads aren't syncing. Stick to JSON or you'll hate yourself.

Version-specific gotcha: Avoid Supabase JavaScript client v2.0.1 - the session refresh is broken and your users will get randomly logged out. We spent 3 days debugging "intermittent auth failures" before downgrading to v1.9.x fixed it.

The Bills That'll Catch You Off-Guard

Here's how Supabase will fuck with your budget: everything counts as egress. API responses? Egress. Real-time updates? Egress. User downloads a profile pic? Egress.

I watched one viral post blow through our 250GB allowance in 6 hours because every view triggered real-time updates.

Tribal knowledge the docs won't tell you: The dashboard lies about connection counts. It shows "active connections" but not the ones stuck in IDLE state that are slowly killing your connection pool. Use SELECT * FROM pg_stat_activity WHERE state != 'idle'; if you want the truth about what's actually hitting your database.

Your typical startup costs:

• Database + compute: $125-200/month
• Auth (because they charge per MAU): $32-50/month
• Storage + egress: $50-150/month (this is where they get you)
• Real-time: $25-100/month
• Total damage: $232-500/month

The pricing jumps are brutal - there's no middle ground between "cheap" and "holy shit expensive". You'll be cruising on the $25 plan until your app gets mentioned on Reddit, then BAM - you're forced into the $225 tier because there's no middle ground.

Real production nightmare: We had a client hit ProductHunt. Connection pool died in 20 minutes - something like 500 concurrent signups, maybe more. Doesn't matter, anything over 200 kills the default pool anyway. Supabase dashboard showed green lights while users got ECONNREFUSED and ENOTFOUND errors. Took 2 hours to realize we needed to upgrade from Micro (0.5 CPU) to Small (2 CPU) compute, not just bump the database plan. Cost them maybe $2K in lost signups while we scrambled.

Check out the compute pricing to understand why this happens. The usage-based billing will surprise you when your "cheap" app suddenly needs enterprise-level resources.

Supabase pricing structure: from "cheap" to "holy shit expensive" with no middle ground

I've built MVPs in 3 days with Supabase that would've taken 3 weeks on AWS. But I've also watched connection pools die during ProductHunt launches. Here's the real story.

The Supabase dashboard: pretty until you need to debug a performance issue

Why Startups Love Supabase (Until They Don't)

The automatic API generation is legitimately magic. Create a table, boom - instant REST API with authentication baked in. No boilerplate, no configuration hell. The dashboard shows you exactly what's happening with your data.

But here's where it gets messy. Works great in development, production is where you learn about connection limits. The free tier is generous until you actually build something people use.

The MVP sweet spot: Under 50,000 MAU, Supabase is pure gold. Above that? You start hitting walls.

The Three Things That'll Kill Your App at Scale

1. Connection Pool Russian Roulette

PostgreSQL has max_connections=100 by default and Supabase doesn't boost this much on their lower tiers. PgBouncer helps but won't save you when 200 concurrent signups hit during a ProductHunt launch. Works fine until traffic spikes and then everything dies with FATAL: remaining connection slots are reserved.

Connection pooling: works great until ProductHunt traffic hits

2. Row Level Security Will Destroy You
RLS policies will murder your performance at scale. Complex policies with JOINs can turn 5ms queries into 200ms nightmares. One startup I know had RLS policies doing SELECT * FROM user_permissions WHERE user_id = auth.uid() on every fucking row - killed their dashboard load times. Had to rewrite their entire auth system because RLS couldn't handle their user growth. Check the performance guide to understand the bottlenecks.

3. Real-Time Subscription Death Spiral
Database subscriptions hit hard limits around 1,000 concurrent subscribers per table due to single-threaded change processing. I watched a live-chat app die because they didn't know this limit existed.

The Bills That Made CEOs Cry

Egress charges sneak up on you - every API call counts. One viral TikTok and you're looking at $2K bills instead of $200.

The staging environment trap: Development environments cost extra, so add $100+ per staging environment. Nobody tells you this upfront.

That $25 tier looks cheap until you need any enterprise features. Point-in-time recovery? $100/month. More than 500 real-time connections? $10 per 1,000.

Supabase compute pricing: $25 to $225 with nothing in between

The Enterprise Integration Nightmare

Unlike AWS's everything-is-connected ecosystem, Supabase lives on an island. Want monitoring? Set up Grafana yourself. Need a CDN? Configure CloudFlare manually. Message queues? Good luck. Check the integrations docs to see what's officially supported.

This shit doesn't matter for MVPs, but it becomes a massive pain when you're trying to build something that won't fall over at 2am.

The Migration Story Nobody Talks About

"It's just PostgreSQL" - yeah, until you try to leave. Real-time subscriptions don't exist in vanilla Postgres. RLS policies need complete rewrites. Storage integration? Start over. Edge Functions? Rewrite for Lambda.

I helped one company migrate off Supabase. Took 4 months and cost $200K in developer time. Plan your exit strategy early or get comfortable being locked in. The migration guides only work one way - getting in, not out.

Plan on 2-3 months minimum if you need to escape, could be 6+ months if you went deep on their fancy features.