When I try to use instruments most of the time I can't identify the threads. I'm assuming these are "internal" threads?
One of the threads was causing the CPU to go up to 100% usage. I didn't change anything in the code, how do I identify what is causing these issues.
CFNetwork might point to background network work. HTTP Traffic instrument can helps to figure out what exactly requested via network.
It can be added to existing trace document by clicking Plus button on the top right named "Library". Find "HTTP Traffic" instrument in the list. Double click on the instrument to add it to current document. Start new recording and reproduce the issue. Network work will be shown on the HTTP traffic track aligned with CPU data. It might give a clue which request cause the issue and narrow down investigation area.