Keep the resistor like it is. You won’t lose power because of it. Instead turn your attention to these things.
The marketing material is giving you your best case. Meaning 3mm solid SOFT wood. With perfect focus and a clean lens.
Meaning no glue, no hard wood, and no guessing the perfect focus.
I have been using my laser on several woods recently and I have learned a lot. In order to cut through wood you can try some of these tips.
Find the the sweet spot for your laser lens. Mine says it can work from 30mm to 120 mm. But I recently found that the optimal distance is 65mm. Find that sweet spot for yours that allows you to get that dot size as small as possible.
Keep a fan blowing to clear the smoke. This will prevent your lens from getting dirty and also make the air clear for the beam to hit the wood at full strength.
Use air assist to blow into your cuts so it clears out some of the debris for multiple passes. I have heard aquarium pumps and compressed air work best. I occasionally use compressed air manually right now.
Test different wood types. Soft wood is better. Avoid wood with glue in it. My laser cut almost 1/2 inch through solid pine and yet couldn’t cut through 1/4 inch ply wood because of the glue.
Cut multiple parallel lines. I use estlcam not light burn. In estlcam you can engrave right on the line and also inside the line and outside the line. This way you can get three passes next to each other so it cuts a wider channel through the wood. Helps to allow debris to be blown out of the way.
Consider replacement lenses. Here is a post of mine about endurance laser lenses like the G2, G7, G8. Laser lens information, specs and 4 pack (Endurance Lasers)
It has some good info about different lens types for different situations. It also talks about how much power can get through each lens type. Then consider buying from another source. I am sure Jtech sells their own lenses.
Last tip and I can’t be sure this works or not. Keep the wood you are cutting warm. On a warm day last week my 5.6 watt laser easily cut through 1/8 inch plywood with glue in 2 passes. The next day was colder and it couldn’t cut through the exact same wood in 18 passes. I have ordered some ceramic heat lamp emitters to test this theory better.