A flintlock is supposed to have a good stiff mainspring, but it must be balanced with the frizzen spring. Too heavy, and the frizzen spring too light, the frizzen will bounce and break your flint off. The other way around, and the frizzen will not open fully. Most of us who have been around for a while, like in the last century and before computers, know this relationship, because we have taken locks like yours and tinkered with them until either they worked better, or had to be replaced with something that did. It is a worthwhile adventure, and rest assured, any and all parts can be replaced from other sources, or you can make them yourself.
But the mainspring on a good flintlock is not like that of a T/C "Hawken", or any of the other coil spring efforts. It needs to have lots of authority, with power from the top of the stroke to the bottom.
When you say you are holding up others on the trail walk, I'm taking it that you mean because of misfires, flash in the pan, and failure to ignite the charge. A lock and the vent, in this case, definitely need help.