Return current Unix timestamp with microseconds
microtime ([ bool $get_as_float = FALSE ] ) : mixed
If used and set to TRUE, microtime() will return a float instead of a string, as described in the return values section below.
By default, microtime() returns a string in the form "msec sec", where sec is the number of seconds since the Unix epoch (0:00:00 January 1,1970 GMT), and msec measures microseconds that have elapsed since sec and is also expressed in seconds. If get_as_float is set to TRUE, then microtime() returns a float, which represents the current time in seconds since the Unix epoch accurate to the nearest microsecond.
Did nothing in 0.00023913383483887 seconds
Did nothing in 0.0001680850982666 seconds
Did nothing in 0.00084805488586426 seconds