up until a few days ago I was using Infuse 4.3.6 (on iOS 11) and everything was working great. Then I upgraded to 4.3.7 and the performance of the app is now greatly deteriorated. When time seeking forward or backward or even just pressing pause and play, it takes exactly 5 seconds until the film starts playing again.
Apple introduced some changes in iOS 11.3 which unfortunately resulted in some issues with seeking in Infuse. We addressed these in the 5.6.10 update which was released in March of this year (Infuse Release Notes | Firecore), but older versions (both v4 and v5) will have this issue with iOS 11.3 and later.