I did find this:
InnerSphereNews, on 14 March 2012 - 09:05 AM, said:
<H5>Now, how will you depict Standard Lasers/Pulse Lasers in MWO? –GB_Krubarax </H5>
<P><STRONG>[DAVID] </STRONG>A standard laser fires a continuous beam that applies damage over time while it remains on. A pulse laser fires a continuous beam that blinks on and off. (Not the blaster bolt style of light ‘bullets’ that fly at the target.) Damage is applied in short bursts each time the laser blinks on. </P>
But it really doesn't say how long the continuous beam takes to complete the shot, fractions of a second like MW4 or many seconds like MW3?