I have been cutting a run of the exact same item (See image below)
The top row is from yesterday and the bottom row is from today. The material is a .13 thick quilted maple board. The ones from yesterday cut out easily at 175 and full power. The ones from today required multiple passes at 150 and full power. In many cases the pieces where too charred to use. You can also see that the engrave has barely darkened the wood on the cuts from today.
I have cleaned the optics twice today (side of the machine, both lenses on the head and the mirror), made sure the lens was positioned correctly and cleaned the fan. At this point, 170 at full power looks like a score.
The unit is a basic and it is 11 months old.