In the interests of helping out anyone else who is having the same issue I was:
I’ve been using a Dell Inspiron 13 (7438) 2 in 1 laptop as my new mobile DAW for about a month or so. Everything was working out great until about a week ago when my projects started experiencing ASIO spikes coupled with audio dropouts, as well as a generally increased ASIO usage.
After various attempts at fault finding, I decided to remove all the Dell ‘bloatware’ that came installed on the laptop - something I should have done when I first got it - and the problem disappeared!
No more ASIO spikes, and ASIO useage is lower and nice and stable.