I would not know. weeblrAMP does not particularly use much CPU but it does use some of course. The main part of the page has to be rendered normally but WP then it is transformed into AMP. There's nothing in weeblrAMP config that you could have done wrong and cause high CPU usage.
Thad said, again, CPU usage must be higher with AMP as there's a transformation to be made. But nothing specially high.