Test build for #523. Not a release.
Built from master at f6623296. Contains the startup changes from #540 and #545: at most three suspended tabs are checked/reloaded at once after a browser restart, restored tabs no longer trigger an unbounded burst of checks, and unresponsive placeholders are recovered instead of staying blank.
Unsigned, loaded as an unpacked extension; it does not auto-update. Same extension ID as the Web Store version: it replaces it. Back up your session and settings first and follow the Help test a fix guide. Instructions in #523.