Demonstrations of two different cold weather Trangia stove arrangements. Non-scientific. No measuring cups to check snow and/or water volumes, no gram scales to measure pre or post burn fuel and/or stove weights. Your mileage may vary. Boil tests are way too dependent on so many different factors to be accurate in all situations.
This video shows the factory Trangia preheating set up (preheating cup and aluminum plate), cup has been modified with a carbon felt pad rather than the original fiberglass pad. The preheating pad burns under the burner, warming the fuel and the burner, allowing for a rapid "bloom" in cold weather.
It also shows a slight variation of wawhiker's felt pad "wick" for instant lighting/instant simmer flame. In my adaptation of this concept, I only have the carbon felt up to the Trangia recommended fill level, and this allowed a pretty rapid "bloom" with no other preheating.
Both of these burners were filled wigh denatured alcohol the night prior to these lightings. The low overnight temperature was 3 degrees Farenheit, and was approximately 5 degrees Farenheit at the time of these demonstrations.
I apologize for the couple choppy edits.