Solve initial lag problem with JavaScript image viewer

I need help fixing a lag issue with a web-based image viewer. We are using ViewerJS, but this problem is not specific to this library; any CSS based zoom to an image element will trigger it. One can use the keyboard shortcuts on the image element (up/down keys). The lag is very obvious the first time zooming in on the image. After that, without switching the tab, everything works nicely and the interaction is smooth. Steps to reproduce the problem: 1. open the attached [login to view URL] in your browser 2. click on the show viewer button 3. zoom in on the image using the keys or pinch-zoom/scroll 4. the lag is clearly noticeable in the beginning while zooming in After switching to a different tab, and going back to the viewer tab, the lag returns. Notes: The browser's native zoom does not have this problem. The lag is present only when zooming in, zooming out is smooth. The bug relates to the Chrome browser, but it is not restricted to it. Task: - find a way to remove this initial, and reoccurring lag on the latest version of Chrome - one should not switch to HTML5 canvas (or derivatives) - the bug needs to be fixed using the current approach for image rescaling, which provides sufficient quality interpolation. The scaled-down versions using canvas show large amounts of either aliasing or blurriness, which is not desirable.