Monitoring & metrics

# Experience website speed yourself

Performance issues manifest as:

• Pages that load slowly with the browser loading icon spinning
• 504 timeout errors appearing on screen

# Check the browser dev tools

Browser dev tools pinpoint whether performance issues originate on the frontend or backend. Open your browser's dev tools and check the network tab first. You can also run a performance audit, such as Lighthouse, to identify bottlenecks in rendering, JavaScript, or resource loading.

# Check the hosting metrics

The fortrabbit dashboard offers a metric section (your hosting provider likely will have something similar) including the following vital data points that help you identify what's causing slowdowns:

• PHP response time: Aim for less than 250ms on average. In our experience, it's more likely that a website with an average high response time will have problems. Slow websites that are getting some more visits than usual are tending to break down (504) faster.
• 5xx error metric: See if there are any peaks in 5xx errors. If there are, see if at the same time, the PHP response time went up, in that case those 5xx errors are likely 504 time out errors.
• Memory usage: Memory usage should not come too close to your hosting limits on average; 80% average usage with occasional peaks is acceptable.
• Memory swap usage: Swap is when there is no (fast) RAM available anymore and data needs to be accessed from disc (slow). This should be within bounds, which depends on your website.
• OpCache: This should usually not max out. Aim for 80% or less. Higher values are usually not a problem.

Once you've identified problematic metrics, see common performance issues for diagnosis steps, or review backend performance best practices for optimization strategies.