If I'm logged into Magento's backend and perform some task that takes a long time (global search on large catalogs, long running dataflow, etc), my web browser will refuse to load other admin pages in that browser only. Why does this happen, and is there any known science for workarounds?

That is, if I

1. Log into Magento's dashboard page

2. Open a second tab with any Magento admin page

3. Perform a long running global search (simulated with a call to sleep(30) at the start of globalSearchAction) in the first tab

4. Attempt to reload the second tab

Expected Behavior: Second tab loads with page contents immediately

Actual Behavior: Second tab only loads once the long running global search completes

Does anyone know, specifically, why this happens? (My guess is Magento admin console requests lock some resource Magento needs to bootstrap, but I don't know what that is)

Does anyone know of a fix/workaround?