Thanks to another customer who sent us his files, it appears that the delayed animation was related to how images were being loading.
You can see if this is the issue you're having if after viewing your content the first time, the content appears to play without delay. The reason for an improvement in this case is due to the content being cached.
To make your content play without delay without having to view the content first in order to cache it, you can adjust how the content loads the first time it is viewed.
When you export either by going to in5 > Export HTML5 with in5... or to in5 > Easy Export Wizard... and click the Advanced button, go to the Advanced section of the Export HTML5 with in5 dialog. If Lazy Load Images is selected, then deselect that option.
I would usually recommend using this setting so that images only load once the user goes to a page. However, if the images are getting loading when the page loads, then that loading time can slow down the playing of the animated content.
You can also improve the loading time of the images by optimizing them. If you have a Gold plan or higher, then you can set Image Optimization in the Advanced section of the export dialog to Enhanced.
If you have a Pro plan or higher, then you can set Image Optimization to Standard.