Why open a pojects running slowly,but import zhe same projects running fastly?

  When AE open a mogrt file(Motion Graphics Template ),it will extract into a folder,then open it. But,when I open this projects ,it's running so slowly,that can hardly preview,edit and modify the file,I can't stand it.

  But when I import this AE project file into an other project,it became normal,preview is so faster,an I able edit and modify this project.In the two between,that open or import this project,I didn't do anything,but the result is were very different.It's really weird and funny,I can't explain this .Has anyone ever been in the same situation?Can you explain to me what this is all about? Thank you very much!

   By the way,this mogrt file is provided by ADOBE AE and anyone can be found in the" ADOBE After Effects CC 2018\Support Files\Essential Graphics\[AE] News Package"folder.