Cubase 10.5.10 Overloads after making minor adjustments to audio

I have a project in Cubase which is pushing my computer to the limit. The project might play through fine. Then, I make a change to a track’s volume automation, for example. Then Cubase will no longer play my track. The cpu meter just pumps as it tries to play it.

Why would making this minor change have a detrimental effect on the performance of Cubase?