Especially when writing your first book, it can be difficult to judge whether you're book is too fast paced. To avoid a fast paced plot right from the start, make sure you plan A LOT. Personally, I always make chapter plans, so I know exactly what will be in each chapter.

If you're already writing your book, and you're uncertain about if your book is too fast paced, take a step back and ask yourself if you would find the plot too fast. You don't want all the dramatic events to happen in the first chapters of the book, but at the same time you don't want to bore the reader with a slow plot.

Instead of writing a lot of drama in each chapter, maybe pick one or two events to happen in each chapter and fully explain and describe them. You don't want your book to be really short because all the fun stuff happens in the first paragraph.

A way to make sure that your chapters don't sound too fast paced is to have a lot of description, and this breaks up events and gives your book a slower pace.