I looked at the performance of my Django app hosted on Render to see it can be improved. My goal is to get response times for most pages to within 100ms. The app itself is in a good state that there are no unnecessary calculations and I’m happy with performance on localhost. The performance on Render however is subpar. In particular, I want to know if there’s a bottleneck somewhere and whether that would be the database or rather the app VM.
curl was used to issue ten consecutive requests and display different timing metrics. I averaged them in a spreadsheet and these are the results (all values in miliseconds):
| dnslookup | connect | appconnect | pretransfer | starttransfer | total | TTFB | |
|---|---|---|---|---|---|---|---|
| Starter (template) | 5.46 | 29.14 | 68.87 | 68.97 | 146.70 | 149.13 | 77.73 |
| Starter (ORM simple) | 7.12 | 30.55 | 70.55 | 70.67 | 309.54 | 345.07 | 238.87 |
| Starter (ORM complex) | 5.08 | 28.22 | 68.65 | 68.77 | 654.63 | 681.49 | 585.86 |
| Standard (ORM simple) | 3.74 | 26.80 | 63.48 | 63.59 | 196.03 | 235.14 | 132.44 |
| Pro (template) | 5.49 | 28.15 | 69.59 | 69.69 | 144.82 | 146.98 | 75.13 |
| Pro (ORM simple) | 4.98 | 27.54 | 68.53 | 68.65 | 195.37 | 228.94 | 126.71 |
| Pro (ORM complex) | 2.83 | 27.98 | 68.65 | 68.77 | 281.73 | 313.07 | 212.97 |
| localhost (template) | 0.02 | 0.41 | 0.00 | 0.46 | 24.83 | 24.89 | 24.38 |
| localhost (ORM simple) | 0.02 | 0.38 | 0.00 | 0.40 | 66.62 | 66.71 | 66.21 |
| localhost (ORM complex) | 0.02 | 0.35 | 0.00 | 0.39 | 189.86 | 189.94 | 189.47 |
- template refers to a Django view that only renders a basic template without issuing any database queries (i.e. a 404, about or imprint page). This serves as a baseline to see how fast the server responds without taking the Postgres VM into account. As Render doesn’t allow downgrading Postgres machines, I could only test with the current tier, which is the Standard level with 1GB RAM and 1 CPU.
- ORM simple is a Django view that renders a template but also runs 6 queries with ~13ms in total (according to Django Debug Toolbar).
- ORM complex is a Django template view with 23 queries that run in 52ms in total.
My laptop has 8 CPU cores and 16 GB RAM. All localhost measurements were all taken using the gunicorn WSGI server with DEBUG=False. The Postgres instance is on Standard level with 1GB RAM and 1 CPU. The app’s VM on Starter level has 512MB RAM and 0.5 CPU while it has 4 GB RAM and 2 CPUs on Pro level. As Render doesn’t allow to downgrade Postgres machines, I couldn’t do the measuring with different database virtual machine tiers.
This is the command I used to do the measurements:
for i in {1..10}; do
curl -w "dnslookup: %{time_namelookup} | connect: %{time_connect} | appconnect: %{time_appconnect} | pretransfer: %{time_pretransfer} | starttransfer: %{time_starttransfer} | total: %{time_total} | size: %{size_download}\n" \
-so /dev/null \
"http://localhost:8000/404/" ;
done
The values up until appconnect (DNS lookup and SSL handshake) look nothing out of the ordinary for me. That’s also what other websites have as well. As browsers cache connection data for subsequent requests anyway, I’m mostly interested in the waiting time / TTFB (starttransfer - pretransfer).
What’s astonishing to me is that rendering a simple template takes 3 times as long on Render on both Starter and Pro (~75ms) machines compared to localhost (25ms). If I could shave off those additional 50ms I’d be very happy.
The fact that a regular page has a waiting time of 127ms even on Render Pro is disappointing considering its high cost. Out of curiosity, I ran the test on a Standard tier as well and got 132ms, which seems like a better price-value ratio for me.
Is it unusual to not have the same performance with Standard / Pro tier VMs as on my localhost?
I’d be interested in your setups and response times. How powerful are the machines that you use?
