Earlier, when you would access the test report of a running test, the number of visitors and conversions shown in the stats table was updated in real-time but other metrics such as improvement and probability to beat baseline (calculated using Bayesian SmartStats) were calculated once every 4 hours. This means when you accessed your test reports, VWO fetched the cached data and generated the report for you.
This was the case because the calculations are resource-intensive and this can lead to confusing situations where your test has updated conversion and visitor data but the improvement rate and other metrics are shown based on old calculations. With some recent optimizations, this does not happen anymore.
Now, whenever you open a test report, VWO fetches the up to date conversion and visitor data, runs Bayesian SmartStats on that data, and generates a report for the test where all metrics are up to date.
Since a running test is continuously getting more visitors and conversion every second, we have also added an option to refresh the test data. You can click on the Refresh data button and VWO will fetch the updated stats for this test. Hovering on the refresh icon also shows you when your data was last updated.