How to solve the problem of lost frame?

Hi , I’m new ? I devoplop a game on ue4 in htc vive. however,when use steam vr, it tell me lost frame warning.I want to know how can I to solve this problem.
I use stat unit to test it ,shows here

94933-qq截图20160617190345.png

my project setting is here

94934-qq截图20160617190427.png

who can give me some help to solve this problem?thanks!