I have noticed this to.
I 'think' its when your using an event sheet which is included by lots of layouts, i'm guessing the layouts have to be stored in memory or something.
My work around with this is to take parts of the code from the main event sheet, and spread them into separate events sheets, and include them in the main event sheet.
So you only have to worry about lag when you want to include a new event sheet.
I have been able to do some quick fix also, but it is not working for me since it makes everything few times longer unfortunatelly.
I have moved all layouts to dummy event sheet and keep only few for testing with original sheet.
I am tracking performance of my laptop all the time and CPU used by C2 is not bigger than 1%, disc usage not bigger than 2-3%, ram usage around 5%, GPU not even close to lag, yet this is the numbers I see when slow down occurs. Very strange imo.