Potential fix for URL bar lag.

[diracdeltas]

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Ran git rebase -i to squash commits (if needed).

Test Plan:

Fix #4360

Auditors: @bbondy

Test Plan:

1. Open a bunch of tabs, or copy over a session-store-1 file with a bunch of tabs
2. Open a new tab and start typing
3. Observe if there is a lag between when you press a key and when the character shows up