Why drag and drop from menu to timeline lags my computer?

Hi! I'm using Hitfilm Express 13 (13.1.0004) on a Macbook Pro 2017 with MacOS Sierra 10.12.5 (the latest version of HF for my OS).

The program works just fine, the thing is that whenever I drag and drop any kind of media or effect it goes really laggy. It's jumping all along the way and takes forever to get to the timeline. When I reach the timeline, it goes back to normal. The same with crossfades, takes forever from the effects list to the exact point of the cut.

It is slowing my workflow a lot. I have no idea of what could it be. Any clue?