I noticed that Lasers(or my assembly table) seem to loose a lot(25%) of power, i have 4 lasers supplied with 80RF/t, but my assembly table just gets ~60 RF per tick which is quite a big loss of power

The setup consists of 2 combustion engines(running on forestry ethanol->40 RF per engine) connected to 4 lasers directly above the assembly table

lol what you say and what's in the picture are different you said there was 4 lasers there are actually 5 and for generators you said 2 when there is 3 be sure to know this before posting XD

Apply more Engines.

BuildCraft does not lose energy unless power loss is enabled in your pack. Also, you want to watch out for power loops - they're a dangerous power.