When diagnosing performance problems it can be valuable to see what Chrome is doing "under the hood." One way to get a more detailed view into what's going on is to use the about:tracing tool.
Note that to understand what's happening in trace events you'll need a basic understanding of how the browser works. The above articles provide enough to get started, but it's recommended to first read at minimum:
Even further reading:
Start by perusing the Tracing Ecosystem Explainer to understand the various different pieces of code involved.