The current into the power triac gate is limited using the highlighted resistor. My triac requires at least 50 mA.
The resistor gets fairly hot during actual operation and no surprise: \$I^2R\$ (RMS) with the 10k resistor I'm using is about 1.2W if my calculations are correct.
Is there a better way to limit the current here, especially one that doesn't involve generating much extra heat? I don't mind spending a few more pennies on a solution that requires less tweaking – in particular, I'd love to just grab a purpose-built DIP6/8 IC that requires only a single additional passive to set the current limit.
I've seen a few circuits using transistors, but I don't have any with a high enough voltage rating, and if I'm going to buy something I'd prefer to buy the most suitable part for the job.