When testing performance using several tools, we often encounter vastly different results. The discrepancy between measurements is not only confusing, but also doesn’t inspire confidence. It becomes difficult to establish which tool to trust. This issue manifests itself when comparing Calibre to other services, in this case, Google’s PageSpeed Insights (pagespeed.web.dev).
It’s not possible to run PageSpeed Insights in a continous manner without development work or a paid service. If PageSpeed is your tool of choice, you can use Calibre’s PageSpeed mode to run performance tests under the same conditions as PageSpeed Insights, with all benefits and features of a robust performance platform.
In this guide, we explain how to emulate PageSpeed in Calibre. We also explain key differences between how both tools measure performance, so you can better understand your performance results.
| Calibre | Calibre PageSpeed mode | PageSpeed Insights | |
|---|---|---|---|
| Test locations | 17 (to choose from) | 17 (to choose from) | 4 (round-robin selection) |
| Devices | 13 | 2 | 2 |
| Connection speeds | 12 | 2 | 2 |
| Device and Network throttling | Runtime. Applied at the time of test | Simulated. Applied after test completes | Simulated. Applied after test completes |
| Automated testing | ✅ Yes | ✅ Yes | ❌ No |
| Performance budgets | ✅ Yes | ✅ Yes | ❌ No |
| Notifications | ✅ Yes | ✅ Yes | ❌ No |
| Integrations | ✅ Yes | ✅ Yes | ❌ No |
To test performance in Calibre with settings mimicking PageSpeed Insights:
It’s important to note that each monitoring service operates under notably contrasting conditions.
The location of where tests originate from is a significant factor in performance testing. The latency for every request will differ from location to location. Your site may be closer, or further based on where the test is ran from.
| Calibre | PageSpeed Insights |
|---|---|
| Tests originate from a pre-selected test location. Run on Amazon Web Services (AWS). | Tests originate from 1 of 4 global locations, based on round-robin selection and latency to your browser. Run on Google. |
Google PageSpeed Insights is hosted in 4 locations:
Network conditions change based on locale, but another important factor is the applied network speed of the test.
| Calibre | PageSpeed Insights |
|---|---|
| Test Profiles allow you to choose from a list of pre-configured network throttling settings. They’re chosen based on their relevance to observed global averages. | PageSpeed tests under two different network speeds: Desktop (described as “Dense 4G 25th percentile”) and mobile (described as “Mobile Slow 4G”). |
The underlaying hardware running performance tests has an effect on the accuracy of simulated hardware devices. Both Calibre and PageSpeed use different types of machines.
In order to return results fast, PageSpeed runs at full network speed, then applies a simulation to calculate performance metrics. This is also true for Calibre’s PageSpeed mode.
Outside of PageSpeed mode, Calibre applies bandwidth and device throttling as it conducts the testing—metrics are recored in realtime.