Severe lag when using multiple alpha channel videos on planes


I’m new to UE4 and taking over porting a project from vizard and it’s about 70% through completion. It is a VR experience where characters are displayed on a plane using .avi video with an alpha channel.

When I add more than two actors (I can get up to 4 on a completely blank level), the videos and their audio begin to lag horribly.

For the level that I’m currently building, there are initially 4 actors on screen, then it goes up to 7, then back down to 5.

Thank you for your help!

Does anyone have any tips for fixing this? How can I optimize the video (currently working with Premiere Pro) or the level to prevent lagging?