Trouble with Gecko/20061024 Firefox/1.5.0.7

Hello
Running ktruss firefox
I get a pretty much endless stream of...

4593 firefox-bin sa_yield                        JUSTRETURN
   4593 firefox-bin gettimeofday(0xbfbfe2f8, 0)     = 0
   4593 firefox-bin gettimeofday(0xbfbfdf58, 0)     = 0
   4593 firefox-bin gettimeofday(0xbfbfdf58, 0)     = 0
   4593 firefox-bin timer_settime(0x3, 0x1, 0xb8fffe18, 0) = 0
   4593 firefox-bin gettimeofday(0xb8ffff10, 0)     = 0
   4593 firefox-bin gettimeofday(0xb8fffed0, 0)     = 0
   4593 firefox-bin timer_settime(0x3, 0x1, 0xb8fffe08, 0) = 0
   4593 firefox-bin gettimeofday(0xb8bfff30, 0)     = 0
   4593 firefox-bin gettimeofday(0xb85fff30, 0)     = 0
   4593 firefox-bin gettimeofday(0xb89fff30, 0)     = 0
   4593 firefox-bin gettimeofday(0xb87fff30, 0)     = 0
   4593 firefox-bin close(0x1c)                     = 0
   4593 firefox-bin close(0x1a)                     = 0
   4593 firefox-bin close(0x1e)                     = 0
   4593 firefox-bin close(0x1b)                     = 0
   4593 firefox-bin close(0x20)                     = 0
   4593 firefox-bin close(0x1d)                     = 0
   4593 firefox-bin close(0x21)                     = 0
   4593 firefox-bin gettimeofday(0xbfbfe0b8, 0)     = 0
   4593 firefox-bin read(0x9, 0xbfbfe3e3, 0x1)      = 1
        "\M-z"

This behaviour doesn't seem to be present when I run
firefox-linux (1.5.0.5)

What is firefox looking for ?
or more helpfully how do I find out what
"firefox-bin gettimeofday" is looking for ?