The dropped frames may not necessarily mean that the content that you are seeing is not smooth or crisp. This is because Camtasia's recorder will analyze the frames and remove duplicate frames. When you play your TREC back in Camtasia, how does the video play?
I've found that if you constrain snagit to a single core (since you have a high end pc this should not be an issue) this problem gets fixed on my end. Might help you. Task manager\Details\(right click)affinity. Hope this helps