i started firefox...

I started firefox, and got the profile selection menu. At that point, top said

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND                                                               
 4534 me        15   0  451m  31m  19m S    0  1.6   0:00.51 firefox-bin

No extensions loaded, no page displayed, nothing. Just the profile selection window.