Hello I am noticing lags spikes when using my mod what ways are there to identify what part of my mod is causing this?

Are you using only your mod, and in a dev environment? It would be useful to know what your mods does or adds to the game first of all

Okay so it is in the dev env and in the "production" use with other mods, my mod is using RestAPIs to request data and displaying UI and data from the api requests.

I have no knowledge of that API so someone else should give you advice on that. You should show your code, or share a link to your repository

Well is there anyway I can see the lag spikes causes from ingame like F3 menu or is it just purely testing and knowing what could cause this?

Oh you're right