What kind of computer do you have?

Not a camtasia expert....i use jingproject to record my videos.

You can check out the camtasia tutorials below

Recording Tutorials for Camtasia Studio

It could be that your PC is just too slow to handle Camtasia. You might not have enough RAM.

Overall Camtasia is a pretty poor product, their support has admitted that it was not created for HD video, and only works best with short videos. Also, their program does not fully support 64 bit, or multi-core systems.

If it was the 1990's, Camtasia would be nice. Maybe in <2005 times. But these days their product is extremely lacking. I would recommend something else.

Check the settings. By default, Camtasia sets the record rate at "automatic" which can result in caapture rates as low as 4fps . Set a standard capture rate (the higher, the smoother) that ties in evenly with your screen refresh rate and you should get a much better result.

Test your audio connections and settings too. If you want to record music, you'll probably want to capture the output from your sound card rather than the microphone. Personally, though, I would save the music as a .wav or .mp3 file and dubb it on during the edit.

You need a pretty powerful PC for video editing and most other programs these days.

Old laptops are the worst!