Other - Missing Keystrokes in Firefox while loading Google Map API

I have a webpage displaying google map with data (all javascripts). Often I chat with people using another program while google map is loading.

I saw missing key strokes when I was typing in chatting window in Firefox, while google map page is loading. But this doesn't happen in Chrome.

In Chrome, all key strokes were displayed from buffer, but in firebox, it seems some key strokes are lost in buffer.

Does Chrome has different key stroke buffer from Firefox?

Does anyone see missing keystrokes in firefox?

Thanks.