Performance issues on Firefox with debugger open

I've been testing my app with SQL.js on Chrome and Firefox. With the debugger closed, queries perform with reasonable (<1ms) query times on both browsers. However, with the debugger open, SQL.js performs as expected on Chrome, but however, on Firefox, queries become much slower (on the order of magnitude of 100ms). This makes debugging quite painful.

Is this a known issue, and are there workarounds?

Thanks.

Start by reproducing the reported SQL.js query timing difference with Firefox's debugger open and closed, comparing it with Chrome. Done means determining whether the debugger-related slowdown is reproducible and documenting a confirmed cause or workaround; the report names no source file or test to begin from.